In the context of lunar geology, which of the following statements best describes the term "Lunar Magma Ocean"?
1
A vast ocean of liquid water that once covered the moon's surface.
2
A hypothesized early stage in the moon's history when its surface was entirely molten.
3
The current state of the moon’s mantle, characterized by its partially molten nature.
4
A region on the moon where volcanic activity is still ongoing.