Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances?

Your answer is B, and I agree. The Montreal Protocol (1987), built under the Vienna Convention for the Protection of the Ozone Layer (1985), sets controlled reduction and phase-out schedules for ozone-depleting substances such as CFCs, halons and carbon tetrachloride. It entered into force in 1989, and India ratified it in 1992.

Why the others are wrong:

• Bretton Woods Conference (1944): it created the IMF and the World Bank to manage the international monetary and financial order. It has nothing to do with the environment.
• Kyoto Protocol (1997): an instrument under the UNFCCC for cutting greenhouse gas emissions, mainly CO2, to fight climate change. It does not govern ozone-depleting substances.
• Nagoya Protocol (2010): under the Convention on Biological Diversity, it deals with access to genetic resources and fair benefit sharing.

Core concept: ozone depletion and climate change are separate problems, though a few substances affect both. After the 2016 Kigali Amendment, HFCs are also being phased down under the Montreal framework, a change that came after this exam. For Mains GS-III (environment), this shows how treaty regimes work and how India meets its commitments.

Trap: students who remember 'Protocol' and 'environment' pick Kyoto by reflex. Anchor each treaty to its subject: ozone with Montreal, climate with Kyoto, and biodiversity benefit-sharing with Nagoya.