Correct answer: A). Decomposition, fossil fuel formation, fossil fuel emission.
The decomposition can be defined as the process that involves the degradation of plant and animal waste below the earth's sediments. This matter that is buried below the earth remain there for millions of years under high pressure and temperature and as a result of that fossil fuel are produced. The burning of these fossil fuels by human results in the emission of carbon into the earth's atmosphere.
Hence, the correct answer would be option A.