Q1. There are several theories existing about the formation of the Moon. The one constraining factor which relates the Earth and the Moon and the possible formation history of the Moon is that :
1. The bulk composition of the Moon is exactly the same as that of the Earth
2. The bulk composition of the Moon is similar to the mantle material of the Earth, although some uncertainties of the detailed composition remain yet to be resolved.
3. The composition of the Moon is similar to Earth's core.
4. The composition of material on the Earth and the Moon are radically different.