Concept:Evaporation slows when liquid molecules find it harder to escape into the vapour phase.
Explanation:Increasing the pressure over the liquid pushes vapour molecules back toward the liquid surface.
This makes it more difficult for liquid molecules to break free and evaporate.
Therefore, an increase in pressure directly lowers the rate of evaporation.
Now check the other options:
Lowering the boiling point makes the liquid vaporise more easily, so evaporation increases.
Decreasing humidity brings drier air, which increases the evaporation rate.
Wind removes vapour above the liquid, so evaporation also increases.
Hence, the only factor that decreases evaporation is increased pressure over the liquid.
Answer:A. increase in pressure over the liquid.