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Home Q & A Board Science-Related Homework Help High School Level Science
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applesauce234 applesauce234
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5 years ago
Earth's first atmosphere was rich in water vapor but poor in free oxygen. The atmosphere became more oxygenated with the
A) development of the ozone layer.
B) emergence of stromatolites that developed a simple version of photosynthesis.
C) emergence of gases from volcanic eruptions.
D) both A and B.
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CatHanCatHan
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5 years ago
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applesauce234 Author
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5 years ago
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