Answer:
The theory of the formation of fossil fuels is that fossil fuels are the remnants of organisms that lived a long time ago and were buried, heated, and formed into hydrocarbons.
Step-by-step explanation:
A is not correct because the nitrogen is not a gas that is dominant in fossil fuels.
B is not correct because the oxygen can not turn to carbon in any manner.
C is correct because the consensus about the formation of fossil fuels is that after the organisms were dying out, they were getting buried (usually in the soft layers of the ocean floor), over time with the higher temperatures and pressure from below managed to change their structure and create hydrocarbons.
D is not correct because there hasn't been any evidence so far that there are fossil fuels on comets and asteroids.