Answer:
The correct answer is- Biogas
Step-by-step explanation:
Anaerobic digestion of animal waste generates biogas which is a mixture of gases like methane, carbon dioxide, nitrogen, hydrogen, hydrogen sulfide, etc. The primary gas present in biogas is methane which constitutes about 50-75% of total biogas.
Anaerobic or fermentative group of bacteria like methanogens, acetogens, etc acts on animal waste and generates these gases over digestion. This is a natural process that is used by humans to produce methane which acts as fuel that gives energy on burning.
This energy can be used to- generate electricity, cooking, heating, steam production, drying, etc.