Which fossil fuel is considered the cleanest, mainly methane?

• A. Coal
• B. Oil
• C. Natural gas
• D. Peat

Answer: (C)

When comparing fossil fuels, the key idea is which one burns with the fewest pollutants per unit of energy. Natural gas is mostly methane, so its combustion produces far fewer sulfur dioxide, particulate matter, and nitrogen oxides compared with coal or oil. It also releases less carbon dioxide per unit of energy because methane has fewer carbon atoms to oxidize and fewer impurities to release during burning. Peat tends to be moist and impure, making it less energy-dense and dirtier to burn, while coal contains more carbon and impurities, and oil releases more pollutants than natural gas as well. So, among these options, burning natural gas delivers the cleanest emissions profile. (Note: methane leaks during extraction and transport can affect overall climate impact, but for combustion alone, natural gas is the cleaner burn.)