A grass snake living in northern England dies of natural causes. After a long period of time, its remains decay in the soil to become fossil fuel. When the fossil fuel is processed, sold, and burned by humans, it releases carbon dioxide into the air. Which aspect of this scenario shows a carbon source becoming a carbon sink?

A.

burning of the fossil fuel

B.

decaying of the snake's remains

C.

dead snake fossilizing underground

D.

respiration by the snake and humans

E.

humans processing and selling the fuel

Answer: C. Dead snake fossilizing underground.

A fossil fuel is the fuel that is formed by natural processes, such as anaerobic decomposition of dead plants and animals underground. These organisms and their remains remain deep inside the depth of numerous layers of soil resulting in fuel produced after millions of years. A carbon sink refers to a natural or artificial reservoir that stores and absorbs atmospheric carbon by physical and biological process. The formation of fossil fuel inside the earth is carbon sink.

Dead snake will be added as a matter on which biological activity called as decomposition will take place. The organic matter of dead snake will be decomposed by microbes in the soil. The organic matter being the source of carbon, after decomposition will become the reservoir of carbon in the form of fossil fuel.

Therefore, dead snake fossilizing underground is the example of carbon source becoming a carbon sink.