Choose the correct alternative from the following : - Assertion (A) : Legumes revive the soil fertility.
Reason (R) : Microbes in the root nodules of legumes fix the atmospheric nitrogen.

Answer: A. Both A and R are true and R is the correct explanation of A.

The root nodules of leguminous plants contain certain nitrogen fixing bacteria which absorb the atmospheric nitrogen and convert it into nitrogeneous compounds useful for the plants reviving soil fertility.