Which is the fifth most common pool where carbon is stored apart from the Earth's crust, ocean, soils, and atmosphere?

[ Answer ]

Fossil Fuel

[ Explanation ]

Fossil fuel is a natural fuel, just like coal and gas. It is formed from the remains of once living things. The organisms were buried and dead, and went through the process of decomposition. There are three main types of fossil fuels which are used for energy provision. The three types are coal, energy and natural gas. In conclusion, fossil fuel is the fifth most common pool where carbon is stored.

Arsenal

Would the answer be plants?