Why does the moon appear to change its shape as seen from earth?

D.
Different parts of the sun lit moon become visible as the moon revolves around earth

This happens because as the moon orbits earth the sun will project light towards it and the reason it seems to glow is because of the reflected light since the moon is white it reflects more light. Think of it as a day and night cycle except it’s on the moon when it becomes night on earth the part of earth facing towards the sun will be lit aka day/morning/afternoon etc
The part of the earth facing away will be dark aka night/midnight/etc.