Fact 1: Carbon cycles quickly between organisms and the atmosphere.

Fact 2: Carbon dioxide is controlled by the carbon cycle.

Given the two facts above, answer the question "what is controlled between organisms and the atmosphere?" with the following options: 
- carbon dioxide
 - sweating
 - temperature
 - air pressure
 - heat energy
 - Pollution
 - energy usage
 - Chemical energy


 

 carbon dioxide        