Which process provides most of the oxygen found in Earth's atmosphere?
A. Fermentation.
B. Photosynthesis.
C. Aerobic respiration.
D. Dehydration synthesis.
Photosynthesis is the process of making organic food (glucose) by combining the hydrogen from water with carbon dioxide. The oxygen from splitting water is released into the atmosphere. Aerobic respiration takes in the oxygen from the atmosphere, dehydration synthesis is a mechanism of building up molecules by removing water, not oxygen, and fermentation is a form of anaerobic respiration which is done in the absence of oxygen.