Question

why do we see the different phases of the moon?
we see the reflected sunlight as the moon rotates on its axis
as the moon revolves around earth, we see the reflected sunlight from our perspective
as the earth revolves around the moon, the angle of reflected sunlight changes
the rotation and the revolution periods of the moon are the same length

Explanation:

The Moon's phases result from its revolution around Earth. As it orbits, the angle at which we see the sunlight reflected off the Moon changes. The Moon does not emit its own light; it reflects sunlight. The rotation of the Moon on its axis (first option) doesn't directly cause the phases. Earth does not revolve around the Moon (third option - it's the other way around). While the rotation and revolution periods of the Moon being the same (fourth option) explains why we always see the same side of the Moon, it's not the cause of the phases.

Answer:

As the Moon revolves around Earth, we see the reflected sunlight from our perspective.