The correct option is A Both A and R are true, and R is the correct explanation for A.
Most of the wells in India have little water for human needs. Thus, it is said that the use of wells is not an ideal way to water crops as it cannot be done for prolonged periods of time. It takes pumps or hand-generated power to draw water from the deep wells, which is a very tedious task when the water requirement is as high as it is in the context of large areas of land.