What most likely brought about the formation of oxygen in the Earth's primitive atmosphere?

Question

Quizplus · Accepted Answer

It is widely accepted that oxygen was first produced in the Earth's atmosphere by photosynthetic bacteria, specifically cyanobacteria, through a process known as oxygenic photosynthesis. This process involves using energy from sunlight to split water molecules, releasing oxygen gas as a byproduct. Over time, the accumulation of oxygen led to the development of more complex life forms that required oxygen for respiration.

What Most Likely Brought About the Formation of Oxygen in the Earth's