Which of the following is not correctly matched?

The correct answer is D. Carbon trading is linked to the Kyoto Protocol (adopted 1997, in force 2005), not the Montreal Protocol. Under Kyoto, emissions trading is one of the flexible mechanisms, along with the Clean Development Mechanism and Joint Implementation.

The other three pairs are correct:

• A: The First World Climate Conference was held in Geneva in 1979, organised under WMO.
• B: The first Earth Summit (UNCED, Rio de Janeiro, 1992) adopted Agenda 21, a plan for sustainable development.
• C: Earth Summit+5 was held at the UN General Assembly special session in New York in 1997, reviewing Rio commitments.

The Montreal Protocol (1987) is about phasing out ozone-depleting substances such as CFCs. Keep the two treaties apart: Montreal for ozone, Kyoto for greenhouse gases. This also links to the GS-III environment syllabus and to Mains questions on climate finance and international climate governance.

Trap: Candidates who remember that Montreal is 'the environment treaty' often pick the wrong pairing without checking which gas or mechanism it governs.