Phases of the moon occur because

Options

A. we can see only that part of the moon which reflects light towards us.
B. our distance from the moon keeps changing.
C. the shadow of the Earth covers only a part of the moon's surface.
D. the thickness of the moon's atmosphere is not constant.

Answer

A

Explanation

Phases of the moon occur because we can see only that part of the moon which reflects light towards us.
Moon does not produce its own light. We are able to see the moon because the sunlight falling on it gets reflected towards us. Thus, we see only that part of the moon from which the light of the sun gets reflected towards us.