Explanation:

- Correct Answer: Option 3 - Methane

- Gobar Gas, commonly known as biogas, primarily consists of methane, which typically makes up about 50-75% of the total composition.

- Option 1 - Propane

- Propane is a component of liquefied petroleum gas (LPG) and not a major component of biogas.

- Option 2 - Butane

- Like propane, butane is also a part of LPG and is not significantly present in biogas.

- Option 4 - Ethylene

- Ethylene is an organic compound often used in the industrial sector and is not found in gobar gas.

Gobar Gas is mainly produced through anaerobic digestion of organic matter such as agricultural waste, manure, municipal waste, and plant material. Its primary use is as a renewable energy source for cooking and electricity generation.