Assertion: Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity and which may be used as fuel.
Reason: The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan to save these major rivers of our country from pollution.

Both Assertion (A) and Reason (R) are correct but R is not the correct explanation of A.

The correct answer is Option (2) - Both Assertion (A) and Reason (R) are correct but R is not the correct explanation of A.

Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity and which may be used as fuel. However, certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane along with CO₂ and H₂ . These bacteria are collectively called methanogens, and one such common bacterium is Methanobacterium. The technology of biogas production was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).

Due to increasing urbanisation, sewage is being produced in much larger quantities than ever before. However the number of sewage treatment plants has not increased enough to treat such large quantities. So the untreated sewage is often discharged directly into rivers leading to their pollution and increase in water-borne diseases.The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan to save these major rivers of our country from pollution. Under these plans, it is proposed to build a large number of sewage treatment plants so that only treated sewage may be discharged in the rivers.