When relative humidity is high above the ocean, what happens to the net rate of evaporation?

Correct answer: The net rate becomes very slow

Correct answer: B, the net rate becomes very slow. Evaporation is the escape of energetic water molecules from the liquid surface into the air. At the same time, some water-vapour molecules return to the liquid; this is condensation. Net evaporation is the difference between the outward and return rates. When relative humidity is high, the air already contains much water vapour, so more molecules return and the difference becomes smaller. Evaporation may still occur, especially if the water is warmer, wind removes vapour, or sunlight supplies energy, but its net rate is generally reduced. A is incorrect because lower humidity usually creates a larger vapour-pressure difference and speeds net evaporation. C is incorrect because humidity changes that difference. D is incorrect: high humidity does not make water boil, and boiling requires a suitable temperature and pressure condition. The word “net” matters: it means evaporation minus condensation, not that no individual molecule can escape. Memory cue: dry air pulls vapour away; humid air slows net evaporation.