The correct answer is D. Acetylene.
Acetylene is a colorless, flammable gas with the chemical formula C2H2. It is the simplest alkyne and the simplest hydrocarbon with a triple bond. Acetylene is a very reactive gas and is used in a variety of industrial processes, including welding and cutting metals.
Butane is a colorless, flammable gas with the chemical formula C4H10. It is a member of the alkane family of hydrocarbons. Butane is used as a fuel in lighters, camping stoves, and other portable appliances.
Methane is a colorless, odorless, flammable gas with the chemical formula CH4. It is the simplest alkane and the main component of natural gas. Methane is used as a fuel in homes and businesses.
Ethylene is a colorless, flammable gas with the chemical formula C2H4. It is a member of the alkene family of hydrocarbons. Ethylene is used in the production of plastics, synthetic fibers, and other chemicals.
Acetylene is the only gas listed that is burned in oxygen, producing a very hot flame, used for welding and cutting metals.