UPSC Prelims 2014— Question 33

Correct answer: Option B. At sufficiently high warming levels, terrestrial ecosystems can shift toward becoming a net carbon source because warming and associated ecosystem changes can increase carbon release. Widespread coral mortality is also a plausible impact under severe warming and ocean warming/acidification. The statements claiming that all wetlands disappear or cereals become impossible everywhere are absolute and scientifically unsupported. Option A: Incorrect. This option does not match the verified answer because its proposition, location, institution, sequence, or combination conflicts with the relevant fact tested in the question. The option reads: “1 only” Option B: Correct. This option is consistent with the governing fact or the valid combination identified in the question. The option reads: “1 and 2 only” Option C: Incorrect. This option does not match the verified answer because its proposition, location, institution, sequence, or combination conflicts with the relevant fact tested in the question. The option reads: “2, 3 and 4 only” Option D: Incorrect. This option does not match the verified answer because its proposition, location, institution, sequence, or combination conflicts with the relevant fact tested in the question. The option reads: “1, 2, 3 and 4” The key Prelims lesson is to test each proposition independently before selecting the combination. Where the question uses words such as 'only', 'all', 'none', 'always' or a precise institutional/geographical association, a single inaccurate component is sufficient to eliminate the option. The answer recorded here follows the official answer key for the question-paper series represented by the uploaded source and has been cross-checked against an independent published key. The explanation is intended for conceptual revision rather than as a reproduction of any third-party solution.