Which of the following is the rate-limiting factor in biogas production?

The major component of biogas is .......

Which of the following gases is useful as an energy fuel?

Study the following flow chart of biogas production and select the correct option for $A, B$ and $C$.
Stage $III$: $C$
Stage $II$: Organic acids $\xrightarrow{B}$ $C$
Stage $I$: Soluble compounds or monomers $\xrightarrow{A}$ Organic acids
(Note: The flow chart shows: Proteins,Fats,Cellulose,Hemicellulose $\rightarrow$ Soluble compounds or monomers $\xrightarrow{A}$ Organic acids $\xrightarrow{B}$ $C$)

$S$ Statement: $Halophilus$ is responsible for the production of biogas. $R$ Statement: $Halophilus$ is an example of the $Bacteria$ domain.

In India,the technology of biogas production was developed mainly by the efforts of which organizations?