The five most prominent pools where carbon is stored include the earth's crust, oceans, soil, atmosphere, and the

Sediment

Reason -

Sediments deposits consists of carbon reserves in the form of preserved fossils beneath the earth crust. The most important type of reserves of fossils are Coal, oil, and natural gas. These on burning produce carbon dioxide or carbon mono-oxide. The carbon deposits in fossils are due to the carbon entrapped in dead organic matter that deposited beneath the earth and under the impact of pressure and heat  got converted into fossils.