Concept:A gaseous fuel is a hydrocarbon gas that burns easily to release energy.Explanation:Butane, CH3−CH2−CH2−CH3 or C4H10, is a gaseous alkane commonly used as a fuel, for example in liquefied petroleum gas.It burns readily in oxygen to produce carbon dioxide and water, releasing heat.The other options are not primarily used as gaseous fuels.Answer:C. CH3−CH2−CH2−CH3