Right answer is (a) Methane
For explanation I would say: Biogas is one of the types of bio fuel that is produced from the decomposition of organic waste. Biogas is known as the environmentally-friendly energy source since it is converting organic waste into energy. The composition of biogas is as follows: – Methane 50-75%, Carbon dioxide 25-50%, Nitrogen 0-10%, Hydrogen 0-1%.