Question

What was the Great Oxygenation Event?

Group of answer choices

when cyanobacteria began producing large quantities of oxygen through the process photosynthesis

when oceans and land mass oxygen reservoirs became full and free oxygen began to build up in the atmosphere

when the percentage of oxygen in the atmosphere rose to 35% 300 million years ago

when fish and amphibians began to breath oxygen 85 million years ago

Answer 1

Answer: when oceans and land mass oxygen reservoirs became full and free oxygen began to build up in the atmosphere

Step-by-step explanation:

Answer 2

When cyanobacteria began producing large quantities of oxygen through the process of photosynthesis.

Step-by-step explanation:

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