Ruminant animals can digest cellulose in their food,whereas human beings are unable to do so. This is because

How deep is the concrete tank built in a biogas plant?

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 $\xrightarrow{B}$ $C$)

The technology of biogas production from cow dung was developed in India largely by the efforts of

Statement $P$: Bacteria produce methane gas due to metabolic processes like anaerobic respiration.
Statement $Q$: Bacteria act on starchy materials.

Methanogens are responsible for -