Most of the carbon in the rocks that form Earth's mantle and crust was stored there when Earth formed. The rest of Earth's carbon is stored in various reservoirs and exchanged in many ways. In a model of the carbon cycle, which process does NOT contribute directly to the storage of carbon within sediment?
A. the deposition of organic carbon from decaying organisms
B. the deposition of dissolved carbon dioxide from the atmosphere
C. the formation of carbon dioxide through metabolism of carbohydrates
D. the formation of fossil fuels from terrestrial organisms under high heat and pressure