The correct answer is option D:
Unequal warming and cooling of land and sea
During the daytime, the land heats up faster than the ocean. Land heats and cools faster than water. When the air above land heats in the morning, it pushes away the cooler and denser air over the sea thus causing the warm air to rise. When the air over land cools in the evening, it sinks pushing the warmer air over the water out of its way.
