Regarding “carbon credits’’, which one of the following statements is not correct

(a)

The carbon credit system was ratified in conjunction with the Kyoto protocol.

(b)

Carbon credits are awarded to countries or groups that have reduced greenhouse gases below their emission quota.

(c)

The goal of the carbon credit system is to limit the increase of carbon dioxide emission.

(d)

Carbon credits are traded at a price fixed from time to time by the United Nations environment programs.