UPSC Prelims 2014— Question 42

Correct answer: Option B. A lichen is a symbiotic association involving a fungus and a photosynthetic partner, traditionally described as an alga in standard textbook treatment. The fungus provides structure, protection and access to minerals and water, while the photosynthetic partner supplies organic nutrients. This association allows lichens to colonize harsh substrates such as bare rock. 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: “algae and bacteria” Option B: Correct. This option is consistent with the governing fact or the valid combination identified in the question. The option reads: “algae and fungi” 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: “bacteria and fungi” 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: “fungi and mosses” 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.