The correct option is C both of these
Biogas and manure are formed by biodegradable wastes. biogas is a gaseous mixture produced as a result of anaerobic decomposition of different types of biodegradable waste. Biogas contains about 60% methane, 40% CO2 along with traces of nitrogen and hydrogen sulphide.
Manure is formed by decomposition of biodegradable wastes. It is useful for plant growth.