1. Why does the moon appear to change throughout each month? * a. The fraction of the moon that is lit by the sun changes.
b. Different parts of the moon become visible from Earth as the moon rotates
c. Different parts of the sunlit area are visible from Earth due to motions in the Earth-sun-moon system.

C

Explanation:

As the Earth moves in relative to the moon the Earth blocks part of the sun from the moon causing only parts of the moon to light up. This BEST answers the question because B is not accurate because it doesn't describe why we actually SEE it. A might be true but it is not the BEST explained.

Hope this helps! (^-^)