Why must the moon travel more than a full orbit around the earth for the full moon to be complete?

The difference between the sidereal and synodic months occurs because as our Moon moves around Earth, the Earth also moves around our Sun. Our Moon must travel a little farther in its path to make up for the added distance and complete the phase cycle.

Because when the moon travels around the earth the sun gets closer and closer because the light on the moon is the reflection of the sun so when it gets closer it makes more of a reflection there for full moon

Explanation:

i am positive it is c. condensing but i may be wrong