Why does the body feel cool when sweat dries?

Correct answer: Heat is taken from the body for evaporation of sweat

Direct answer: B. Sweat cools the body because evaporation needs energy, and that energy is taken as heat from the skin and nearby body surface. When sweat changes from liquid to water vapour, the faster, more energetic molecules escape first. The remaining skin loses heat, so its temperature and the sensation of warmth decrease. Moving air can make this process faster, and dry air usually allows faster evaporation than already humid air, but the basic reason is heat absorption during evaporation. Option A is wrong because ordinary sweat does not need to freeze to cool the body. Option B is correct. Option C is wrong because dust is unrelated to the cooling mechanism. Option D is wrong because air movement can actually assist evaporation. Memory cue: evaporation takes heat; condensation gives heat back.