UPSC Prelims 2015— Question 5

Correct answer: Option B. Tropical cyclones generally need sufficiently warm ocean water, abundant moisture, a pre-existing disturbance and adequate Coriolis force. The South Atlantic and south-eastern Pacific tropical regions have comparatively cool sea-surface conditions, which inhibit the sustained convection needed for cyclone formation. The ITCZ does not occur there often enough is not the principal explanation. Option-wise analysis: Option A: “Sea surface temperatures are low” is incorrect. It does not match the specific fact, definition, institutional role, geographical association, or constitutional/economic principle required here. The key distinction is the one identified in the core explanation, so this option can be eliminated. Option B: “Inter-Tropical Convergence Zone seldom occurs” is correct. It directly matches the factual or conceptual requirement tested by the question and is supported by the principle explained above. Option C: “Coriolis force is too weak” is incorrect. It does not match the specific fact, definition, institutional role, geographical association, or constitutional/economic principle required here. The key distinction is the one identified in the core explanation, so this option can be eliminated. Option D: “Absence of land in those regions” is incorrect. It does not match the specific fact, definition, institutional role, geographical association, or constitutional/economic principle required here. The key distinction is the one identified in the core explanation, so this option can be eliminated. Prelims takeaway: Focus on the precise institutional role, constitutional provision, geographical association, or technical definition being tested. UPSC questions often place a broadly familiar fact beside a narrowly incorrect qualifier; identifying that qualifier is essential for elimination.