Which Theory About the Origin of the Moon Is Now

Which theory about the origin of the Moon is now believed to be CORRECT?

A) Earth and the Moon formed together, already orbiting each other.
B) The Moon formed separately in a different part of the solar nebula and was later captured by Earth.
C) Earth was spinning so rapidly while still molten that a piece spun off to form the Moon.
D) An object about the size of Mars crashed into Earth, and debris from the collision formed the Moon.