Which statement best describes the carbon cycle?

The statement that best describes the carbon cycle emphasizes the crucial role of carbon dioxide in the process of photosynthesis and respiration. In this cycle, plants absorb carbon dioxide from the atmosphere through photosynthesis, using it to create glucose and releasing oxygen as a byproduct. During respiration, both plants and animals break down glucose to release energy, which involves inhaling oxygen and exhaling carbon dioxide. This process effectively returns carbon dioxide back into the atmosphere, showcasing the cyclical nature of carbon as it transitions between different forms and entities in the environment.

The other statements fall short in accurately representing the carbon cycle. For example, the assertion that carbon shifts only between land plants and animals overlooks the significant contributions of oceans, soil, and geological formations in the carbon cycle. Additionally, stating that carbon is released entirely during combustion fails to recognize that combustion only accounts for specific pathways of carbon release and that carbon is also released through respiration and organic decay. Lastly, the claim that carbon is only found in the atmosphere is incorrect, as carbon is present in various forms across the Earth's biosphere, lithosphere, and hydrosphere, including in living organisms and fossil fuels.