The right option is; gas
Propane is most likely a gas.
Propane gas is a flammable hydrocarbon, and one of the liquefied petroleum gases. Propane is produced from petroleum refining and natural gas processing. Propane gas can be liquefied at very low pressures. Propane is commonly used as fuel in cooking, heating, and also for aerosol propellants, refrigerants, and in motor vehicles.