How did oxygen (O₂)get into Earth's atmosphere?
A)It was outgassed from volcanoes.
B)It was captured from the solar nebula.
C)It came from chemical reactions with surface rocks.
D)It was released by life through the process of photosynthesis.

Question

Quizplus · Accepted Answer

Oxygen was released by life through the process of photosynthesis. Early photosynthetic organisms, such as cyanobacteria, evolved the ability to produce oxygen as a waste product during photosynthesis. Over time, the accumulation of oxygen in the atmosphere led to the formation of the protective ozone layer, which allowed for the development of more complex life forms.

How Did Oxygen (O₂)get into Earth's Atmosphere