The source of oxygen in atmosphere is due to? A)Photosynthesis B)Excretion C)Nitrogen fixation D)Respiration
Option A) The main source of atmospheric free oxygen is photosynthesis, which produces sugars and free oxygen from carbon dioxide and water. The organisms that carry out photosynthesis include the plant life of the land areas as well as the phytoplankton of the oceans. 6CO2 + 6H2O + energy → C6H12O6 + 6O2
