The rocks of the Moon are older than Earth rocks. The Earth has free standing water, but the Moon does not. The Earth and the Moon are gravitationally locked together. The chemical composition of Moon rocks is similar to Earth rocks.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Some scientists have suggested that the Moon was formed when a large body struck Earth and broke off a piece of Earth billions of years ago. Which observation would best support this suggestion?
Possibilities:
- The rocks of the Moon are older than Earth rocks.
- The Earth has free standing water, but the Moon does not.
- The Earth and the Moon are gravitationally locked together.
- The chemical composition of Moon rocks is similar to Earth rocks.

The chemical composition of Moon rocks is similar to Earth rocks.