💥UPSC 2027,2028 Mentorship (April Batch) + Access XFactor Notes & Microthemes PDF

Type: Prelims Only

  • Social Media: Prospect and Challenges

    AI Content Detectors to Combat Deepfakes

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Emerging Technologies; Deepfake Technology;

    Why in the News?

    During the General Elections 2024, the proliferation of AI-generated content (AIGC), including deepfake videos featuring prominent figures like Aamir Khan and Ranveer Singh, raised concerns about misinformation.

    What is Deepfake Technology?

    • It is a type of Artificial Intelligence used to create convincing images, audio and video hoaxes. Deepfakes often transform existing source content where one person is swapped for another.
    • Creating such content involves a technique known as Generative Adversarial Networks (GANs), comprising Artificial Neural Networks.

    Legal Safeguards in India:

    • The regulations under the IT Act of 2000 and 2021 requires social media intermediaries to promptly remove deepfake content. Failure to do so may result in imprisonment or fines.
      • Section 66D: It penalizes individuals for cheating through personation using communication devices or computer resources. (Imprisonment for up to 3 yrs and a fine of up to 1 lakh rupees)
      • Rule 3(1)(b)(vii): This rule mandates that social media intermediaries prevent the hosting of content impersonating others.
      • Rule 3(2)(b): This rule requires social media platforms to remove such content within 24 hours of receiving a complaint.

    Significance of Deepfake Technology:

    • Promotes Right to Expression: Deepfakes amplify voices of marginalised individuals, enabling them to share important messages. Recently, a video was created to deliver the final message of a journalist killed by the Saudi government, calling for justice.
    • Can contribute to the Education System: Online educators use deepfakes to bring historical figures to life for engaging lessons. For example, a video of Abraham Lincoln delivering his Gettysburg.
    • Provides Autonomy: Deepfakes empower individuals to control their digital identity and explore new forms of self-expression. For instance, the Reface App.
    • Provides a realistic experience: Artists leverage deepfakes for creative expression and collaboration, as seen in Salvador Dali’s interactive museum promotion. Deepfake tech enables realistic lip-syncing for actors speaking different languages, enhancing global accessibility and immersion in films.
    • Renovating old memories: Deepfakes aid in restoring old photos, enhancing low-quality footage, and creating realistic training materials for public safety.

    What are the limitations of Deepfake Technology?

    • Spreading False Information: Deepfakes can purposefully spread misinformation, influencing public opinion or elections, like the videos of politicians/celebrities can manipulate viewers and create confusion about important issues.
    • Frauds: Deepfake technology enables impersonation for financial frauds, tricking individuals into revealing sensitive information. They can also fuel harassment, especially targeting women, and lead to psychological distress.
    • Accuracy: While no AI detector guarantees 100% accuracy, tools like Originality.ai boast a 99% true positive rate. Detection models report probability scores, allowing for nuanced assessments despite inherent uncertainties.

    Future Scope:

    • Adversarial AI: Keeping pace with evolving generative AI models poses a significant challenge for content detectors.
    • Accessibility and Cost: With increased adoption and advancements, the accessibility and affordability of detection tools are expected to improve.

    PYQ:

    With the present state of development, Artificial Intelligence can effectively do which of the following? (2020)

    1.       Bring down electricity consumption in industrial units

    2.       Create meaningful short stories and songs

    3.       Disease diagnosis

    4.       Text-to-Speech Conversion

    5.       Wireless transmission of electrical energy

    Select the correct answer using the code given below:

    (a) 1, 2, 3 and 5 only

    (b) 1, 3 and 4 only

    (c) 2, 4 and 5 only

    (d) 1, 2, 3, 4 and 5

  • Artificial Intelligence (AI) Breakthrough

    GPT-4o: A Free AI Model with Vision, Text, and Voice

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Emerging Tecnologies; GPT-4o;

    Why in the News?

    • OpenAI has launched GPT-4o- a version of the GPT-4 model which powers its ChatGPT.
    • It offers enhanced speed, intelligence, and efficiency across text, vision, and audio, revolutionizing human-to-machine interaction and opening up new possibilities for users worldwide.

    About GPT-4o:

    • GPT-4o offers GPT- 4 level intelligence with improved speed and efficiency, making human-to-machine interaction more natural and seamless.(focuses on emotional aspects)
    • It integrates transcription, intelligence, and text-to-speech functionalities seamlessly, eliminating latency and enhancing voice mode capabilities.

    Features of GPT-4o

    • Free Access for All: Previously available only to paid users, GPT-4o now provides advanced tools to all users, unlocking over a million GPTs from the GPT store and expanding possibilities for developers.
    • Multilingual and Vision Capabilities: GPT-4o supports over 50 languages and includes vision capabilities, enabling users to upload photos, documents, and access real-time information during conversations.
    • Real-time Conversations: It is able to understand user emotions and provide emotive styles of conversation in real-time.
    • Vision and Coding Support: GPT-4o can solve complex math problems, assist with coding queries, interpret complex charts, and analyze facial expressions in real-time.
    • Translation and Efficiency: GPT-4o offers live real-time translation capabilities and is two times faster, 50% cheaper, and offers 5 times higher rate limits compared to GPT-4 Turbo.

    PYQ:

    [2020] With the present state of development, Artificial Intelligence can effectively do which of the following?

    1. Bring down electricity consumption in industrial units
    2. Create meaningful short stories and songs
    3. Disease diagnosis
    4. Text-to-Speech Conversion
    5. Wireless transmission of electrical energy

    Select the correct answer using the code given below:

    (a) 1, 2, 3 and 5 only

    (b) 1, 3 and 4 only

    (c) 2, 4 and 5 only

    (d) 1, 2, 3, 4 and 5

  • Forest Conservation Efforts – NFP, Western Ghats, etc.

    Preserving Rajasthan’s Semal Trees 

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Semal Trees and its habitat

    Mains level: NA

    Why in the News?

    Despite its ecological importance, rampant harvesting of Semal Trees for bonfires poses a grave threat to their existence, undermining biodiversity and cultural heritage alike.

    About Semal/ Silk Cotton Trees

    • The Semal tree, scientifically known as Bombax ceiba, is a deciduous tropical tree.
    • It is native to India, South-East Asia, and Northern Australia.
    • It can grow up to 60 meters tall. It has a distinctive straight trunk, often with spiky thorns, and a wide, spreading canopy.
    • It produces vivid red flowers that are large and attractive, making it quite conspicuous when in bloom.
    • The fruit of the Semal tree is a capsule that contains several seeds surrounded by a fibrous, cotton-like substance which is wind-dispersed.

    Commercial Uses

    • The fibers extracted from the fruit, known as kapok, are used for stuffing pillows, mattresses, and life jackets due to their buoyancy and insulating properties.
    • The wood is soft and is often used for making paper, while in rural areas, it is used as fuelwood and for making cheap furniture.

    Ecological Significance

    • Members of tribal communities consume the tree’s reddish root for food during the monsoons.
    • Larvae of the moth Bucculatrix crateracma feed on its leaves.
    • The golden-crowned sparrow weaves the lining of its nests with white cotton from its seeds.

    Felling of a Semal Tree: Which laws are violated?

    1. Rajasthan Forest Act 1953: This act prohibits various activities in reserved forests without prior permission. Specifically, it bars any unauthorized person from felling, uprooting, damaging, or otherwise harming trees. Violating these prohibitions can lead to penalties including imprisonment, fines, or both, depending on the severity of the offence. Semal tree is not recorded in the state’s list of ‘rare, threatened, and endangered’ species. (Trees on this list enjoy priority conservation efforts.) (Indian Kanoon)​
    2. Forest (Conservation) Act 1980: This act is more comprehensive at the national level and was enacted to provide for the conservation of forests and to regulate deforestation. It requires that any non-forest use of forest land must have prior approval from the Central Government. This includes clearances for felling trees, which are only granted under specific conditions that ensure the conservation and sustainable use of forest resources.​ (UNEPLawEnvAssistantPlat)​

    PYQ:

    [2015] In India, in which one of the following types of forests is teak a dominant tree species?

    (a) Tropical moist deciduous forest

    (b) Tropical rainforest

    (c) Tropical thorn scrub forest

    (d) Temperate forest with grasslands

  • Foreign Policy Watch: India-Iran

    India, Iran sign 10-year contract for Chabahar Port Operation

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Chabahar Port, Persian Gulf Mapping

    Mains level: NA

    Why in the news?

    • India and Iran signed a 10-year agreement for the operation of the Chabahar port, marking a significant milestone in their cooperation.

    Back2Basics: Chabahar Port

    • The port is located in southeastern Iran in the Sistan-Baluchistan province, on the Gulf of Oman and at the mouth of the Strait of Hormuz.
    • It is called the “Golden Gate” to Central Asian land-locked countries of Afghanistan, Turkmenistan and Uzbekistan.
    • It serves as Iran’s only oceanic port and consists of two separate ports named Shahid Kalantari and Shahid Beheshti.
    • It is only about 170 km west of the Gwadar port if Pakistan.
      • The development of Chabahar port was initiated by India with a MoU in 2015 and executed in 2016 during PM Narendra Modi’s visit to Iran.

    About the Agreement

    The contract, signed between Indian Ports Global Ltd. (IPGL) and Port and Maritime Organisation (PMO) of Iran, involves substantial investment and development initiatives.

    • IPGL will invest approximately $120 million in equipping the Shahid-Behesti terminal, enhancing the port’s efficiency and capacity.
    • India has extended a credit window of $250 million for mutually identified projects aimed at improving Chabahar-related infrastructure, emphasizing its commitment to regional development.

    Strategic Importance of Chabahar Port to India

    • Chabahar port will boost India’s access to Iran, the key gateway to the International North-South Transport Corridor that has sea, rail and road routes between India, Russia, Iran, Europe and Central Asia.
    • Chabahar port will be beneficial to India in countering Chinese presence in the Arabian Sea which China is trying to ensure by helping Pakistan develop the Gwadar port.
    • India can bypass Pakistan in transporting goods to Afghanistan.

    Economic Significance

    • Chabahar Port is at an important point on the Arabian Sea, with easy access from India’s west coast.
    • Kandla port in Gujarat is the closest port at 550 nautical miles, while the distance between Chabahar and Mumbai is 786 nautical miles.
    • Since 2019, the port has handled more than 80,000 twenty-foot equivalent units (TEUs) of container traffic and more than 8 million tonnes of bulk and general cargo.
    • The port also offers an alternative route from the Strait of Hormuz for cargo traffic between Central Asian countries and Afghanistan.

    PYQ:

    [2017] What is the importance of developing Chabahar Port by India?

    (a) India’s trade with African countries will enormously increase.

    (b) India’s relations with oil-producing Arab countries will be strengthened.

    (c) India will not depend on Pakistan to access Afghanistan and Central Asia.

    (d) Pakistan will facilitate and protect the gas pipeline installation between Iraq and India.

  • Indian Army Updates

    [pib] Exercise Shakti

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Exercise SHakti and another bilateral exercise between India and France

    Mains level: NA

    Why in the news?

    The 7th edition of the India-France Joint Military Exercise SHAKTI begins at Umroi, Meghalaya, signalling the start of a biennial training event aimed at enhancing bilateral military cooperation.

    About Exercise Shakti

    • Shakti Exercise is a joint military exercise between the armies of India and France.
    • It is a biennial training event conducted alternatively in India and France
    • It started in 2011, and since then, the armies of both countries have undertaken it to promote defence cooperation and interoperability.
    • Objectives:
    1. To bolster joint military capabilities for multi-domain operations in a sub-conventional scenario under Chapter VII of the United Nations Mandate.
    2. To operate in semi-urban and mountainous terrain, focusing on achieving a high degree of physical fitness and refining tactical drills.

    Major Defence Exercise between India and France:

    • Garuda: It is the joint air exercise between the Indian Air Force and the French Air and Space Force.
    • Varuna: It is the joint naval exercise between the Indian Navy and the French Navy.
    • Desert Knight-21: It was a bilateral air exercise conducted by the Indian Air Force and the French Air and Space Force at Air Force Station Jodhpur from January 20-24, 2021. It was unique as it involved the fielding of Rafale aircraft by both sides.
    • FRINJEX: It was the maiden joint military exercise between the Indian Army and the French Army conducted at Pangode Military Station, Thiruvananthapuram, Kerala on March 7-8, 2023.

     

    Tap to read more about:

    Various Defence Exercises in News

  • Festivals, Dances, Theatre, Literature, Art in News

    [pib] Ramcharitmanas, Panchatantra, and Sahrdayaloka-Locana enter ‘UNESCO’s Memory of the World Asia-Pacific regional register’

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: MOW register, ramcharitmanas, Panchatantra, and Sahrdayāloka-Locana

    Mains level: NA

    Why in the news?

    The Ramcharitmanas, Panchatantra and Sahrdayaloka-Locana have been included in ‘UNESCO’s Memory of the World Asia-Pacific regional register’.

    About UNESCO’s ‘Memory of the World (MOW) Asia-Pacific regional register’

    Details
    History and Establishment Initiated in 1992 by UNESCO.

    Asia-Pacific Regional Committee (MOWCAP) was set up in 1998.

    Parent Organization Overseen by UNESCO (United Nations Educational, Scientific and Cultural Organization).
    Objective To safeguard, preserve, facilitate access to, and increase awareness of documentary heritage. Focuses specifically on the Asia-Pacific region.
    Examples of Inscribed Items Includes items like Japan’s “Sugihara’s Visas for Life”, Australia’s “Mabo Case Manuscripts”, and Vietnam’s “Ba Chuc Massacre Archives”.
    Impact and Outreach Supports preservation, digitization, accessibility of documents; provides grants and organizes workshops, meetings, and exhibitions to promote knowledge sharing.
    Reference

    About the Texts

    • Ramcharitmanas:

    • Written by Tulsidas in the 16th century, the Ramcharitmanas is an epic poem in Awadhi, a dialect of Hindi, and is a retelling of the Sanskrit epic Ramayana.
    • It narrates the life of Lord Rama, his virtues, the ideals of Dharma, and his reign during Ram Rajya.
    • Hanuman Chalisa is a combination of 40 verses from the same epic.
    • Panchatantra:

    • The Panchatantra is a collection of ancient Indian animal fables that dates back to at least the 3rd century BCE. 
    • Originally written in Sanskrit by Vishnu Sharma.
    • Its stories are crafted as simple yet vibrant narratives that aim to impart practical life lessons through the interactions of anthropomorphized animals.
    • Sahrdayaloka-Locana

    • The Sahrdayaloka-Locana is a Sanskrit treatise on poetics written by Jagannatha Paṇḍitaraja in the 17th century.
    • It is considered one of the most important works of Sanskrit literary criticism.
    • The text discusses the concept of “Sahrdaya“, which refers to a sensitive or discerning reader or critic.

     

    PYQ:

    [2016] With reference to the cultural history of India, the memorising of chronicles, dynastic histories and epic tales was the profession of who among the following?

    (a) Shramana

    (b) Parivraajaka

    (c) Agrahaarika

    (d) Maagadha

  • Wildlife Conservation Efforts

    Species in news: Himalayan Magpies 

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Himalayan Magpies

    Mains level: NA

    Why in the news?

    Blue magpie species are frequently observed from Kashmir to Myanmar.

    About Himalayan Magpies

    • Magpies belong to the Corvidae family, which also includes crows, jays, and ravens.
    • These birds are typically noisy and inquisitive, often featured as omens in folklore around the world.
    • Species Distribution and Habitat:
      • Gold-billed Magpie (Urocissa flavirostris): Also known as the yellow-billed blue magpie, this species inhabits high altitudes between 2,000 and 3,000 meters above sea level, thriving in the high-altitude zones of the Himalayas from Kashmir to Myanmar.
      • Red-billed Magpie: Found at slightly lower altitudes than the gold-billed magpie.
      • Blue Magpie: Occupies lower altitudes and is more likely to be found near human settlements. It builds nests in rhododendron trees.
    • IUCN Status: ‘Least Concerned’

    Observations:

    • The best sightings of yellow and red-billed magpies are along a trekking corridor in Western Sikkim, which spans from tropical forests at lower altitudes to Alpine landscapes.
    • Over 250 species of birds have been documented in this region, with significant bird activity around 2,500 meters.

    PYQ:

    [2014] If you walk through countryside, you are likely to see some birds stalking alongside the cattle to seize the insects, disturbed by their movement through grasses.

    Which of the following is/are such bird/birds?

    1. Painted Stork
    2. Common Myna
    3. Black-necked Crane

    Select the correct answer using the code given below.

    (a) 1 and 2

    (b) 2 only

    (c) 2 and 3

    (d) 3 only

  • Innovations in Biotechnology and Medical Sciences

    Decoding C. Elegans Worm: A Remarkable Discovery

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: C. Elegans Worm

    Mains level: NA

    Why in the news?

    Researchers at Princeton University found that Caenorhabditis elegans can inherit the ‘knowledge’ to avoid a disease-causing bacterium, Pseudomonas vranovensis, across several generations after initially consuming it.

    C. Elegans: Breakthrough made in Scientific Research

    • C. elegans can inherit the ‘knowledge’ to avoid a disease-causing bacterium, Pseudomonas vranovensis, across several generations after by consuming it.
    • The study revealed that the worms ingested small RNA (sRNA) molecules from P. vranovensis, which then altered their feeding behaviour to avoid the bacteria.
    • This sRNA interacts with the worm’s gene maco-1, affecting its neurological functions.
    • These sRNAs are passed down to at least four subsequent generations, demonstrating a form of transgenerational epigenetic inheritance.

     

    About C. Elegans Worm

    • C. elegans, or Caenorhabditis elegans, is a small, transparent nematode (roundworm) widely used in scientific research.
    • It is about 1 mm in length, making it easy to study under a microscope.
    • It has a simple body plan, which simplifies many types of biological research.
    • C. elegans was the first multicellular organism to have its entire genome sequenced in 1998.

    Key Features of C. Elegans Worm

    • Short lifespan and quick regeneration: It has a short lifespan of about 2-3 weeks and develops from an egg to an adult in just 3-5 days. This allows for quick generation turnover and facilitates studies on genetics and developmental biology.
    • Transparency:  It allows researchers to easily observe its internal structures and developmental processes in real time.
    • Genetic information: This has provided a wealth of genetic information and made it a powerful tool for genetic studies.
    • Consistent Somatic Cell Count: Adult C. elegans have exactly 959 somatic cells, and their lineage has been fully mapped, providing a consistent model for studying cell development and death.

    PYQ:

    [2021] Consider the following:​

    1. Bacteria​

    2. Fungi​

    3. Virus​

    Which of the above can be cultured in artificial/synthetic medium?​

    (a) 1 and 2 only

    (b) 2 and 3 only

    (c) 1 and 3 only

    (d) 1, 2 and 3

  • Global Geological And Climatic Events

    Aurora Borealis: What are Northern and Southern lights? Why do they occur?

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Auroras and its types, Coronal Mass Ejections/ Solar Storm

    Mains level: NA

    Why in the news?

    • In a rare event, the night sky over Hanle village in Ladakh was illuminated by the northern lights or aurora borealis.
      • Concurrently, the southern lights, or aurora australis, were observed in New Zealand and Australia.

    What are Auroras?

    • Auroras are natural light displays that appear as bright, swirling curtains in the night sky.
    • They are typically seen near the Poles but can occasionally be observed at lower latitudes.
    • These lights can display a range of colors, including blue, red, yellow, green, and orange, due to the interaction of solar particles with different gases in the Earth’s atmosphere.
    • The phenomenon is known as:
    1. Aurora borealis in Northern Hemisphere and
    2. Aurora australis in Southern Hemisphere

    What causes Auroras?

    • Interaction with Earth’s Magnetic Field: As the solar wind approaches Earth, it interacts with the planet’s magnetic field, causing some charged particles to enter the atmosphere near the poles.
    • Interaction with Gases: These particles interact with gases in the upper atmosphere, producing colourful flashes of light. Collision with oxygen produces green light, while interaction with nitrogen results in shades of blue and purple.

    Reasons for Aurora in Ladakh:

    • Intense Solar Activity: Auroras can extend to lower latitudes during periods of intense solar activity, such as solar flares and coronal mass ejections (CMEs).
      • The CMEs are from the AR13664 region of the sun that has produced several high-energy solar flares
    • Localized magnetic anomalies: Variations in Earth’s magnetic field could potentially influence the occurrence of auroras in specific areas, including regions at lower latitudes.

    Impact on Tech Infrastructure 

    • Auroras can pose challenges to space-dependent technologies and operations.
    • Disruptions in Global Positioning Systems (GPS), radio communications, flight operations, power grids, and space exploration endeavors may occur during such events.

    PYQ:

    [2022] If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth?

    1. GPS and navigation systems could fail.
    2. Tsunamis could occur at equatorial regions.
    3. Power grids could be damaged.
    4. Intense auroras could occur over much of the Earth.
    5. Forest fires could take place over much of the planet.
    6. Orbits of the satellites could be disturbed.
    7. Shortwave radio communication of the aircraft flying over Polar Regions could be interrupted.

    Select the correct answer using the code given below:

    (a) 1, 2, 4 and 5 only
    (b) 2, 3, 5, 6 and 7 only
    (c) 1, 3, 4, 6 and 7 only
    (d) 1, 2, 3, 4, 5, 6 and 7

     

  • The Crisis In The Middle East

    India backs Palestine’s bid for full UN membership

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: UN and its membership; Rights and privileges enjoyed by UN Member

    Mains level: NA

    Why in the news?

    India has voted in favour of a UN General Assembly resolution recommending Palestine’s admission as a full member of the United Nations.

    Arab push for Palestine’s Membership

    • The emergency special session was convened by the Arab Group, with the UAE presenting the resolution in support of Palestine’s full membership.
    • The resolution calls for the Security Council to “reconsider” Palestine’s membership favourably, based on its determination that Palestine is qualified for UN membership.
    • The resolution received overwhelming support, with 143 votes in favour, including India’s, nine against, and 25 abstentions.
    • As an observer state, Palestine currently lacks voting rights in the General Assembly and cannot nominate candidates to UN organs.

    India’s Stance on Palestine:

    • In 1988, India recognized the State of Palestine.
    • In 1996, India opened its Representative Office to the Palestine Authority in Gaza, later relocating it to Ramallah in 2003.

    About United Nations

    Details
    Background  Resulted from the devastation of World War I and II

    Highlighted the need for a more effective international body to maintain peace and prevent future conflicts.

    Predecessor The League of Nations, created in 1919 after World War I, aimed at peacekeeping but failed during World War II.
    The Atlantic Charter Issued in August 1941 by President Franklin D. Roosevelt (USA) and Prime Minister Winston Churchill (UK), this document outlined principles for a post-war world and set the stage for the UN’s creation.
    Naming The term “United Nations” was coined by President Roosevelt in 1941 to describe the allied nations opposed to the Axis powers.
    Declaration by United Nations On January 1, 1942, representatives from 26 Allied nations, including India under British colonial rule, signed this declaration in Washington DC, formalizing their alliance and war objectives.
    Official Formation UN was officially established on October 24, 1945, when its Charter was ratified by 51 member countries

    It included 5 permanent Security Council members: France, Republic of China, Soviet Union, UK, and US.

    First General Assembly The inaugural meeting of the UN General Assembly took place on January 10, 1946.
    Core Goals
    1. To maintain international peace and security.
    2. To foster friendly relations among nations.
    3. To cooperate in solving international problems and in promoting respect for human rights.
    4. To be a centre for harmonizing the actions of nations in attaining these common ends.
    India’s Role India was a founding member of the United Nations, having signed the initial Declaration alongside 25 other Allied nations during World War II.

     

    Rights and Privileges:

    • The rights and privileges of member states in the United Nations are designed to ensure that all members can effectively participate in the organization’s activities and benefit from its resources.

    PYQ:

    [2022] With reference to the “United Nations Credentials Committee”, consider the following statements:

    1. It is a committee set up by the UN Security Council and works under its supervision.
    2. It traditionally meets in March, June and September every year
    3. It assesses the credentials of all UN members before submitting a report to the General Assembly for approval.

    Which of the statements given above is/are correct?

    (a) 3 only
    (b) 1 and 3
    (c) 2 and 3
    (d) 1 and 2