Why is the contribution of tropical oceans to atmospheric water vapour large?

Correct answer: Because both heat and a broad water surface are available there

Correct answer: A. Evaporation requires both a supply of liquid water and energy to give water molecules enough motion to escape from the surface. Tropical oceans provide an enormous, continuous water surface, and the tropics receive strong solar heating through much of the year. Warm conditions generally increase the capacity of air to hold water vapour, while winds and air movement can also carry vapour away from the surface and support continuing evaporation. A is correct because it combines the two basic factors: abundant water and available heat. B is wrong because oceans are major sources of evaporation. C is wrong because the tropics have air and active atmospheric circulation. D is wrong because tropical seawater is liquid, not solid. Memory cue: tropical ocean evaporation needs heat plus open water.