Answered

Scientists infer that oxygen in Earth’s atmosphere

did not exist in large quantities until after

(1) the first multicellular, soft-bodied marine

organisms appeared on Earth

(2) the initial opening of the Atlantic Ocean

(3) the first sexually reproducing organisms

appeared on Earth

(4) photosynthetic cyanobacteria evolved in

Earth’s oceans

Verified Answer :

Glauxeira

Photosynthesis is the process of converting carbon dioxide into oxygen. Oxygen didn't really exist in the atmosphere until photosynthetic organisms appeared and evolved.

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