UPSC Prelims 2021— Question 39

Many bacteria and fungi can be grown on artificial culture media when the medium supplies appropriate nutrients and conditions. Viruses generally cannot be cultured on ordinary cell-free artificial media because they require living host cells for replication. Therefore bacteria and fungi are the correct pair. The final answer-key position for Set C identifies option A as the correct option. Option A — 1 and 2 only — is correct because it is the alternative that matches the constitutional, historical, geographical, scientific or economic principle established above. Option B — 2 and 3 only — is not correct because it does not satisfy the specific condition tested in the question; it represents an alternative that is contradicted, incomplete, or less precise than the accepted answer. Option C — 1 and 3 only — is not correct because it does not satisfy the specific condition tested in the question; it represents an alternative that is contradicted, incomplete, or less precise than the accepted answer. Option D — 1, 2 and 3 — is not correct because it does not satisfy the specific condition tested in the question; it represents an alternative that is contradicted, incomplete, or less precise than the accepted answer. For PYQ interpretation, the distinction between the correct alternative and merely related facts is important. UPSC often places plausible distractors beside the precise statement that matches the underlying rule, chronology, definition or empirical relationship. The answer should therefore be read against the exact wording of the question rather than against a broadly related fact.