What is one way carbon returns to the atmosphere?

Carbon returns to the atmosphere primarily through exhalation by living organisms. This process occurs during cellular respiration, where organisms, including humans and animals, metabolize food to release energy. As a byproduct of this metabolic process, carbon dioxide is produced and expelled back into the atmosphere when organisms breathe out.

This cycle is a fundamental part of the carbon cycle, as it helps maintain the balance of carbon in the environment. The carbon dioxide released during exhalation contributes to the atmospheric pool of carbon, which is essential for various biological and ecological processes, including photosynthesis in plants.

Other options are related to different aspects of the carbon cycle but do not directly facilitate the return of carbon to the atmosphere in the same way. For instance, photosynthesis captures carbon dioxide, while vegetation growth sequesters carbon, and precipitation does not play a direct role in atmospheric carbon levels. Thus, the process of exhalation stands out as a clear and direct mechanism for carbon returning to the atmosphere.