Answer: B). Decomposition, fossil fuel formation and emissions.
Decomposition is the process in which complex organic matter are converted into simpler substances. Decomposition of animal waste which can be found in the form of animal flesh, fur, bones, hair, faeces etc. This decomposition takes place wiithout air. These animal remains buried inside the earth are converted into fossil fuels. These fossil fuels remain inside the earth for millions of years until they are searched and dug out. These fossil fuels are used by humans as a source of non-renewable energy and they are liberated in the atmosphere as fossil fuel emissions.