Evidence suggests that originally the Earth's atmosphere contained a large amount of carbon dioxide and almost no oxygen. Our atmosphere is different today: it contains a large amount of oxygen, which is good, since we need it to breathe
What caused this atmospheric change?
A)
Global warming
B)
A meteor impact
C) Photosynthetic organisms like cyanobacteria taking in carbon dioxide and
releasing oxygen
D) Photosynthetic organisms like cyanobacteria taking in oxygen and
releasing carbon dioxide