Question

which describes oxygen content as earth evolved over time? oxygen levels sharply declined about 400 million years ago. oxygen levels stay above 15 percent starting 200 million years ago. oxygen levels remain below 5 percent starting 1000 million years ago. oxygen levels raise significantly between 1000 and 700 million years ago.

Explanation:

By observing the graph, oxygen levels stayed above 15 percent starting 200 million years ago. Oxygen levels did not sharply decline about 400 million years ago, were not below 5 percent starting 1000 million years ago, and did not significantly rise between 1000 - 700 million years ago.

Answer:

Oxygen levels stay above 15 percent starting 200 million years ago