wait... hold up... no... maybe... never.
I am going to assume you are working on a test or a quiz. Please provide your answer choices becuase I might have taken the same test or quiz as you recently. (:
The answer i believe is d.
hope this helps!!
I think it’s a, hopefully you get it right!
Answer:
A
Explanation:
Today, the atmosphere holds about 21 per cent oxygen. ... When the first simple organisms appeared in the oceans more than 3.5 billion years ago, the atmosphere was mostly nitrogen, hydrogen, water vapor, and carbon dioxide
