A. Carbon dioxide
B. Carbonates absorbed from soil
C. Oxides of minerals
D. Photosynthesis carried out by plants, algae, and some bacteria.
¨ The oxygen that keeps us alive comes mainly from photosynthesis carried out by plants, algae, and some bacteria.
¨ During photosynthesis, these organisms use energy from sunlight to convert carbon dioxide and water into oxygen and carbohydrates (sugar molecules).
Submitted by :- Jamil Ahmed