Question

which process contributed to the formation of earths early atmosphere?
differentiation
outgassing
crystallization
respiration

Explanation:

Outgassing is the release of gases (such as water vapor, carbon dioxide, etc.) from the Earth's interior. In the early Earth, volcanic activity led to outgassing which contributed to forming the early atmosphere. Differentiation is the separation of Earth into layers. Crystallization is about formation of crystals. Respiration is a biological process (not relevant to early Earth atmosphere formation as life was not prominent then).

Answer:

outgassing