If water is available at the surface but air is cool and nearly saturated, why will evaporation remain limited?

Correct answer: Because both energy and vapour-accepting capacity will be low

Direct answer: A is correct. Having water at the surface is necessary for evaporation, but it is not sufficient by itself. First, cool conditions give water molecules less kinetic energy, so fewer molecules can escape from the surface. Second, cool air has a lower saturation capacity than warm air. If it is already nearly saturated, it has little remaining ability to accept additional water vapour. Thus both the energy supply for escape and the atmospheric vapour-deficit condition are unfavourable. Evaporation can still occur, but its rate is limited and may be balanced partly by condensation. A is correct because it includes both controlling factors. B is wrong: available water provides the material for evaporation; it does not stop the process. C is wrong because cold air still contains gases. D is wrong because saturated air is moisture-rich relative to its temperature, not dry. Memory cue: evaporation needs water, energy, and room in the air for more vapour.