Carbon can be found in shells and
sedimentary rock at the bottom of
oceans in the form of

The correct answer to the following question will be "Limestone".

Explanation:

Carbon dioxide has always been typically accumulated throughout the ocean by organic compounds, whether as gasification agent or, throughout a longer period, as carbonate rocks elsewhere in the seafloor.When individuals die, everyone's shells fall straight to the bottom including its ocean's surface and thus become sediments including limestone as well as organic cement.

So that the above would be the right answer.

The answer will be d