Concept:Basin irrigation is a controlled method of flooding that helps to conserve water.
Explanation:In basin irrigation, the land is divided into enclosed basins surrounded by low earth banks.
Water is directed into each basin and allowed to stand until it soaks into the soil.
Because the water is trapped within the basin, it does not run off or spread beyond the required area.
This reduces the amount of water lost, ensuring that crops receive enough moisture without waste.
Option C is wrong because basin irrigation is generally a simple and inexpensive method.
Option A describes the trapping of alluvium, but it is not the main advantage of basin irrigation.
Option B is not the primary benefit, since the method mainly focuses on efficient water use.
Answer:D. water is not wasted