UPSC Prelims 2021— Question 24

Bisphenol A is a monomer/intermediate used prominently in producing polycarbonate plastics and epoxy resins. It is not the characteristic structural component of low-density polyethylene, polyethylene terephthalate or ordinary polyvinyl chloride. Concerns about BPA relate particularly to its migration from certain food-contact materials and its endocrine activity. The final answer-key position for Set C identifies option B as the correct option. Option A — Low-density polyethylene — 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 B — Polycarbonate — is correct because it is the alternative that matches the constitutional, historical, geographical, scientific or economic principle established above. Option C — Polyethylene terephthalate — 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 — Polyvinyl chloride — 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.