This is also called as a bio gas

The correct option is bio methane.

Step-by-step Explanation:

Biogas is a mixture of gases produced by the anaerobic decomposition (breakdown in the absence of oxygen) of organic matter, such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, or food waste.

The primary component of biogas is methane (${\mathrm{CH}}_4$), typically making up about 50% to 75% of the mixture, with carbon dioxide (${\mathrm{CO}}_2$) making up most of the remainder, along with small amounts of other gases like hydrogen sulfide and moisture.

When biogas is purified and upgraded to remove carbon dioxide, water, and other trace contaminants, it reaches a high concentration of methane (usually more than 97%). This purified gas is chemically identical to natural gas and is specifically referred to as biomethane (or bio-methane). Because methane is the primary active, energy-producing component of biogas, biogas is frequently referred to or identified directly as biomethane in various fuel and energy contexts.