The correct option is (b) Deep Surface Drains
The best I can explain: These drains carry both discharge from shallow surface drains and the seepage water from underground. To carry the seepage water from underground, a cunnette of about 0.6 m depth is provided at the center of the drain. The cunnette is lined void weed growth, and to withstand high velocities. It is fully operative only in rainy season because otherwise the flow will be confined in the cunnette only.