UPSC Prelims 2018— Question 87

**Concept and analysis:** Most coral reefs occur in warm tropical and subtropical waters because reef-building corals require suitable temperature, light and water chemistry. Australia, Indonesia and the Philippines contain a very large share of the world's coral reef area. Coral reefs also support exceptionally high biodiversity, although comparing 'number of animal phyla' with tropical rainforests is a specialised claim; the question's official combination treats all three statements as correct. The question is testing precise UPSC-level identification rather than a broad association. The key is to distinguish the exact institutional, constitutional, historical, geographical, economic or scientific feature being asked. **Option-wise evaluation** **Option A:** Incorrect. It selects 1 and 2 only, but that combination does not match the verified statement-level assessment; it either includes a false statement or omits a true one. **Option B:** Incorrect. It selects 3 only, but that combination does not match the verified statement-level assessment; it either includes a false statement or omits a true one. **Option C:** Incorrect. It selects 1and 3 only, but that combination does not match the verified statement-level assessment; it either includes a false statement or omits a true one. **Option D:** Correct. It selects statements 1, 2, 3; these are the statements supported by the relevant constitutional, economic, historical, scientific or geographical facts. **UPSC takeaway:** The safest way to solve this type of question is to anchor the answer in the defining feature of the concept and then test every option against that feature. Closely related institutions or terms are often used as distractors. In statement-based questions, do not judge the option as a whole before checking each statement independently. In factual questions, compare the wording of each option with the exact definition, location, institutional role, chronology or scientific property. The correct answer follows from that verification rather than from familiarity with a keyword.