Answer the following question given this paragraph: 

Cellular respiration and photosynthesis are important parts of the carbon cycle. The carbon cycle is the pathways through which carbon is recycled in the biosphere. While cellular respiration releases carbon dioxide into the environment, photosynthesis pulls carbon dioxide out of the atmosphere. The exchange of carbon dioxide and oxygen during photosynthesis ( Figure below ) and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.


Q: Cellular respiration and photosynthesis are important parts of which cycle?

 Choices:

- vapor cycle

- greenhouse effect

- water cycle

- carbon cycle

A:
carbon cycle
