Most likely, oxygen was first released into the atmosphere by
A) the decomposition of dead organisms
B) plants
C) cyanobacteria
D) oxidation reactions

Question

Quizplus · Accepted Answer

Cyanobacteria, also known as blue-green algae, were the first organisms to perform oxygenic photosynthesis, releasing oxygen as a byproduct. This oxygen gradually accumulated in the atmosphere, eventually leading to the oxygen-rich atmosphere we have today.

Most Likely, Oxygen Was First Released into the Atmosphere by