The biogas is a mixture of ________.

Biogas is a mixture in which methane is the main fuel gas along with hydrogen and other gases.

Methane with ethane does not describe biogas, as ethane is not a notable part of it.

Ethanol with methane is wrong, since ethanol is a liquid fuel, not a biogas component.

Oxygen with butane is incorrect, as free oxygen is absent and butane is not produced.

Biogas forms when bacteria break down organic waste without air, yielding mostly methane with carbon dioxide.

Its high methane content makes biogas a clean cooking and lighting fuel in rural areas.