The correct options are
B It happens during the night.
D Gentle breeze flows from the land onto the sea.
During night, the sea cools down slowly as compared to the land. Hence the sea would be warmer than the land. So, the warmer air over the sea rises and creates a low pressure area below. This results in the cooler air from the land flowing onto the sea. This cool gentle breeze is called the 'land breeze'.