●Carbon and hydrogen are the main constituents of a fuel. In addition to them, fuel also contains sulfur, oxygen and nitrogen in minimal quantities.

●Depending on the fuel, the percentage of carbon ranges from 50-95%, hydrogen (H₂) 2-6%, oxygen (O₂) 2-4%, sulfur (S₂)  0.5-3% and nitrogen (N) 5-7%.

●Since the major combustion elements in fuel are carbon and hydrogen, fuels are also called as hydrocarbon.

Hence, the correct option is (D).