The correct answer is C. ethane.
Ethane is a chemical compound with the chemical formula $C_2H_6$. It is the simplest alkane and the main component of natural gas. Ethane is a colorless, odorless gas that is lighter than air. It is flammable and can be used as a fuel.
Propane is a chemical compound with the chemical formula $C_3H_8$. It is a colorless, odorless gas that is heavier than air. Propane is flammable and can be used as a fuel.
Butane is a chemical compound with the chemical formula $C_4H_{10}$. It is a colorless, odorless gas that is heavier than air. Butane is flammable and can be used as a fuel.
Methane is a chemical compound with the chemical formula $CH_4$. It is the simplest alkane and the main component of natural gas. Methane is a colorless, odorless gas that is lighter than air. It is flammable and can be used as a fuel.
The name of a compound is determined by its molecular formula. The molecular formula of a compound tells us how many atoms of each element are present in the compound. The name of a compound is based on the number of carbon atoms in the compound.
The name of a compound with one carbon atom is methane. The name of a compound with two carbon atoms is ethane. The name of a compound with three carbon atoms is propane. The name of a compound with four carbon atoms is butane.