The Majority of Oxygen in Earth's Atmosphere is a Product

Question

The majority of oxygen in earth's atmosphere is a product of photosynthesis by ______.
A) agricultural lands
B) microorganisms
C) rain forests
D) green plants

Accepted Answer

Microorganisms, particularly cyanobacteria and phytoplankton in the oceans, are responsible for producing a significant portion of the Earth's oxygen through photosynthesis.