The correct answer is A-2, B-1, C-3, D-4. Explanation & Key Takeaways: • Montreal Protocol → Ozone Depletion: The Montreal Protocol aims to phase out substances that damage the ozone layer, such as chlorofluorocarbons (CFCs). Hence, A-2 is correctly matched. • Ramsar Convention → Wetlands: The Ramsar Convention focuses on the conservation and sustainable use of wetlands, recognising their ecological and economic importance. Hence, B-1 is correctly matched. • Basel Convention → Hazardous Waste: The Basel Convention regulates the transboundary movement and disposal of hazardous wastes to protect human health and the environment. Hence, C-3 is correctly matched. • UNCCD → Desertification: The United Nations Convention to Combat Desertification (UNCCD) addresses land degradation and desertification, especially in arid and semi-arid regions. Hence, D-4 is correctly matched. • All four protocol/convention–objective pairs are correctly matched. • Hence, the correct option is 3. Related Concepts: • Montreal Protocol • Adopted in 1987 under the Vienna Convention for the Protection of the Ozone Layer. • Targets phase-out of ozone-depleting substances (ODS) such as CFCs, halons, and HCFCs. • Widely regarded as one of the most successful global environmental agreements, with measurable recovery of the stratospheric ozone layer underway. • Ramsar Convention on Wetlands • Adopted in 1971 in Ramsar, Iran. • Promotes conservation and wise use of wetland ecosystems, including marshes, lakes, mangroves, and coastal habitats. • Member countries designate internationally important sites known as Ramsar Sites for protection. • Basel Convention • Adopted in 1989 to regulate international movement of hazardous and toxic waste. • Aims to minimise waste generation and ensure environmentally sound disposal. • Restricts dumping of hazardous waste from developed to developing countries. • United Nations Convention to Combat Desertification (UNCCD) • Adopted in 1994 following the Rio Earth Summit process. • Focuses on combating desertification, drought, and land degradation. • Encourages sustainable land management and restoration of degraded ecosystems. • Explanation of All Matching Options • Option 1: Incorrect because it mismatches Montreal with wetlands and Ramsar with ozone depletion. • Option 2: Incorrect because it wrongly links Ramsar with hazardous waste and Basel with wetlands. • Option 3: Correct as all conventions are accurately paired with their objectives. • Option 4: Incorrect because it swaps Basel and UNCCD objectives.