Which organizations are developed for biogas technology?

$A$ is a methane-rich fuel gas produced by $B$ breakdown with the help of $C$ bacteria. Here $A, B$,and $C$ refer to:

The type of gases produced during the process in biogas plants depends on which of the following?

$A$ : Methanogens can show symbiotic association with eukaryotic organisms.
$R$ : They are used for the production of biogas.

Methanogens,particularly $Methanobacterium$,grow anaerobically on cellulosic material and produce:
$I.$ Methane
$II.$ Carbon dioxide
$III.$ Oxygen
$IV.$ Ethane
Choose the correct option.

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