Normal temperature of human body is 98.4 °F. Its equivalent temperature in °C is?

Use the conversion C = (F − 32) × 5/9. Here, (98.4 − 32) = 66.4, and 66.4 × 5/9 = 332/9 ≈ 36.89 °C. So the answer is B.

The other options fail when you convert back to Fahrenheit. Option A (40.16 °C) is about 104.3 °F, a high fever. Option C (35.72 °C) is about 96.3 °F, which is on the low side. Option D (32.36 °C) is about 90.2 °F, which would indicate severe hypothermia. Only B lands near 98.4 °F, the normal oral reading.

The core concept is the Celsius–Fahrenheit relation, which is basic arithmetic. For the exam, the more useful habit is a quick sanity check: normal body temperature is about 37 °C (98.6 °F), so any answer far from 37 is wrong. This kind of unit-conversion reasoning recurs in Prelims science questions and in Mains answers on health and public hygiene.

Trap: Aspirants sometimes subtract 32 but forget to multiply by 5/9, or multiply by 9/5 by mistake. Both errors produce a number that looks plausible but is far from 36.9.