The correct answer is (a) CH4.
CNG stands for compressed natural gas. It is a mixture of methane (CH4) and other hydrocarbons, such as ethane (C2H6) and propane (C3H8). CNG is a clean-burning fuel that produces fewer emissions than gasoline or diesel fuel. It is also a more efficient fuel, meaning that vehicles that use CNG get better gas mileage than those that use gasoline or diesel fuel.
CO2 is carbon dioxide, a greenhouse gas that contributes to climate change. N2 is nitrogen, an inert gas that does not react with other substances. H2 is hydrogen, a flammable gas that is not used as a fuel in automobiles.
CNG is a safe and reliable fuel that can help to reduce pollution and improve air quality. It is also a cost-effective fuel that can save money on fuel costs.