asked 41.9k views
3 votes
Until the early _______ there were only negligible amounts of free oxygen in the atmosphere.

A. Cenozoic
B. Mesozoic
C. Proterozoic
D. Precambian

asked
User Himayan
by
8.2k points

2 Answers

1 vote
C Proterozoic is the answer I just took the test hope this is very help 
answered
User Brian Gesiak
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7.6k points
4 votes
Just took the test it's D. proterozoic
answered
User Andrii Shvydkyi
by
8.0k points
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