What Has Created at Least Half of the Oxygen in Earth's

Question

What has created at least half of the oxygen in Earth's atmosphere?
A) burning fossil fuels
B) trees in the boreal forest
C) phytoplankton in the ocean
D) plants, algae, and phytoplankton in the intertidal zone

Accepted Answer

Phytoplankton in the ocean are responsible for at least half of the oxygen in Earth's atmosphere through photosynthesis. Trees in the boreal forest and plants, algae, and phytoplankton in the intertidal zone also contribute oxygen, but not as significantly as phytoplankton. Burning fossil fuels does not create oxygen, but instead releases carbon dioxide into the atmosphere.