Assertion (A): For farmers rainfall is still the most important source of water.

Reason (R): Irrigation canals and tanks have been constructed by rulers since ancient times.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Both A and R are true but R does not explain A.

Explanation — Farmers make use of irrigation canals and tanks, as well as rely on rainfall. However, they are two separate facts.