Why can perceived temperature feel higher when humidity increases?

Correct answer: Because sweat evaporation decreases and body cooling becomes weaker

Direct answer: A is correct. The human body loses heat partly when sweat on the skin evaporates. For evaporation to continue efficiently, the surrounding air must be able to accept more water vapour. When relative humidity is high, the air is already close to saturation, so the difference between the moist skin and the surrounding air is smaller. Sweat then evaporates more slowly, less heat is carried away, and the body may feel warmer than the measured air temperature suggests. This is why humidity contributes to heat discomfort and to heat-index estimates. A is correct because it identifies the weakened evaporative cooling mechanism. B is wrong because humidity does not turn the body into fire. C is wrong because thermometers can measure temperature in moist air. D is wrong because water vapour does not create the Sun. The effect is strongest when humidity is high and the air is warm; it is a comfort effect, not necessarily a rise in the actual thermometer reading. Memory cue: high humidity blocks sweat evaporation, so cooling feels weaker.