Answer: Option (1)
Explanation: In the given picture, we can mark the location or the area where a dam must be constructed.
At region 1, where there is extreme moisture and water content comparatively high, a dam should be constructed which will facilitate the water to flow from the dam to the drought affected areas such as region 2 and 3.
Water salinity can also be reduced and thus the place possibly won't face drought.
Thus the correct answer is option (1).