Scientists believe that early plants released oxygen in a process called photosynthesis. Where did the carbon dioxide needed for photosynthesis come from in the early atmosphere?
A)
Volcanoes released carbon dioxide
B)
The Earth captured carbon dioxide from space with its gravity.
C)
Water molecules on the Earth were broken to release carbon dioxide.
D)
Early bacteria and plants released carbon dioxide as well as oxygen when
they performed photosynthesis