(i) Both A and R are correct and R is the correct explanation of A.

Explanation: Excessive use of chlorinated synthetic pesticides causes soil and water pollution. This is due to the fact that fertilizers slowly get accumulated in the water bodies and start hindering with others too. This in turn cause several problems as they start migrating from one place to other water bodies with the help of rain. Also, pesticides are chemicals which can not be decomposed or degraded using the microorganisms. Therefore, they are non-biodegradable.