The residue left after methane production from cattle dung is:
a. burnt
b. buried in landfills
c. used as manure
d. used in civil construction.

Solution:

Option (c) is the answer

Because it provides certain organic compounds and minerals to the soil, the residue remaining after methane production from calf dung is used as manure.

As a result, the right response is ‘used as manure.’