The correct option is D natural gas
Natural gas is formed primarily of methane, it also includes ethane, propane, butane, and pentane.
Coal gas constitutes hydrogen and methane with small amounts of other hydrocarbons, carbon monoxide, carbon dioxide, and nitrogen.
Water gas constitutes carbon monoxide, hydrogen, and small amounts of methane, carbon dioxide, nitrogen.
Producer gas constitutes CO,N2,H2,CH4,CO2,H2O,NH4.