Biogas is prepared from

Biogas is produced through anaerobic digestion of organic matter known as biomass. Biomass includes agricultural waste, animal dung, sewage, and other organic materials. Option D correctly identifies biomass as the raw material for biogas production. Options A (petrol), B (kerosene), and C (minerals) are all incorrect as they are fossil fuels or inorganic substances that cannot produce biogas through biological processes.