Step 1: Key Environmental Milestones.
- 1972: The United Nations Conference on Human Environment in Stockholm marked the first major global environmental discussion.
- 1985: The Vienna Convention for the Protection of the Ozone Layer was established.
- 1987: The Brundtland Commission Report popularized the idea of sustainable development.
- 1997: The Kyoto Protocol to the UNFCCC imposed legally binding greenhouse gas reduction targets on developed nations.
Step 2: Ordering the Milestones.
The correct chronological sequence is:(A) A: United Nations Conference on Human Environment in Stockholm (1972)(B) B: Vienna Convention for the Protection of the Ozone Layer (1985)(C) D: Brundtland Commission Report (1987)(D) C: Kyoto Protocol to the UNFCCC (1997)
Step 3: Solution.
Therefore, the correct order is (B) A, B, D, C.