Carbon is a fundamental element of all living things. Carbon atoms move continiously through living organisms (biosphere), the sea (hydrosphere), the land (geosphere), and the air (atmosphere). This continious movement is known as the carbon cycle. Photosynthesis and respiration are a very important part of carbon cycling. Which diagram correctly depicts the cycling of carbon through photosynthesis and respiration?

Worldwide circulation and reutilization of carbon atoms, chiefly due to metabolic processes of living organisms. Inorganic carbon, in the form of carbon dioxide, is incorporated into organic compounds by photosynthetic organisms; when the organic compounds are broken down in respiration, carbon dioxide is released. Large quantities of carbon are "stored" in the seas and the atmosphere, as well as in fossil fuel deposits.