The correct answer is (b) (ii) and (iii).
Explanation:
Small check dams are primarily built across flooded gullies to slow down the water flow, which prevents soil erosion by trapping sediment behind the dam. They also allow the water to percolate into the ground, recharging the groundwater table.
Why other options are incorrect:
(i) and (iv):
While check dams can hold water for irrigation, they don’t hold it permanently. The water is retained temporarily to prevent erosion and recharge groundwater, but it eventually flows out or is absorbed into the soil.
(c) (iii) and (iv):
Although check dams do recharge groundwater, the “permanent” water holding aspect is incorrect. They temporarily store water to slow erosion and recharge groundwater.
(d) (ii) and (iv):
Option (d) is incorrect because check dams do not permanently hold water. They are designed to slow down water flow and trap sediment to prevent erosion and recharge groundwater.