Concept:Higher relative humidity means the air already holds more moisture, so it cannot absorb much extra water vapour.
Explanation:Sweat evaporates when water vapour moves from the skin into the surrounding air.
This movement depends on the difference in water vapour pressure between the skin and the air.
As relative humidity increases, the air gets closer to saturation.
Since saturated air has little capacity to take in more water vapour, evaporation slows down.
Therefore, the rate of evaporation of sweat from the human body decreases when relative humidity increases.
Answer:A. decreases