Biogas is produced by
aerobic breakdown of biomass
anaerobic breakdown of biomass
with the help of methanogenic bacteria
Both 2 and 3
As we have already studied in Microbes in Production of Biogas -
Biogas
wherein -
During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulfide and carbon dioxide. These gases form biogas and can be used as source of energy as it is inflammable.
Hence, the correct option is (d).