What causes the moons revolution around the earth?

Question

I'm studying for a test 

Answer 1

Maybe better to say, gravity *keeps* the Moon in orbit. The *initial* cause of the angular momentum and kinetic energy that the Moon had (and still partially has) was the geometry of its formation event, a collision of Earth with a quite massive, but still somewhat smaller body early in Solar System history, which ejected considerable debris.

Answer 2

Gravity. And it's the "moon's" revolution, "not moons."