Answer:
the biosphere
Explanation:
The carbon cycle is crucial for the circling of energy in the biosphere. This is due to the usage of the carbon by the living organisms, especially the ones that are producers. The producers are able to perform photosynthesis, thus making their own food, but this process requires carbon, and without the carbon it will not be possible. The producers are the basis of all ecosystems, so the energy they produce is transferred through the trophic levels. Ones the organisms die, the carbon is taken by the producers again, and the process continues, with the energy circling around constantly.