Answer:
C. The atmosphere
Explanation:
The atmosphere is chock-full of carbon due to emissions from living organisms, geological processes, and the production of energy by humans. Trees obtain most of their carbon from atmospheric carbon due to its abundance. Also, the sun provides them with the light energy for photosynthesis, while decaying organisms provide ammonia.
Their formulas are opposites.photosynthesis is used to make food In plants and respiration is used to make energy.