Question

A major source of oxygen on Earth is?

1) ozone
2) ocean based phytoplankton
3) animals
4) decomposition of water in the oceans

Answer 1

The major source of oxygen on Earth is phytoplankton, which release over 50% of the oxygen produced on Earth through photosynthesis.

Step-by-step explanation:

The major source of oxygen on Earth is phytoplankton. Phytoplankton release over 50% of the oxygen produced on Earth through photosynthesis.

Photosynthesis by bacteria, algae, plankton, and plants generates atmospheric oxygen, allowing humans and other oxygen-dependent organisms to survive. The free oxygen produced by photosynthesis began accumulating in our atmosphere about 2.4 billion years ago.

Therefore, option 2) ocean-based phytoplankton is the correct answer.