The correct option is D Loss of agricultural land which leads to unemployment.
Few disadvantages of constructing a dam are:
1. Displacement of tribal people, as area has to be vacated where dam will be constructed.
2. The area where dam is being constructed, farmers losses their agricultural land which eventually increases unemployment.
3. Animals, vegetation from the place where dam is constructed will be displaced, leads to high loss of forests, flora and fauna.
4. Reservoir Induced Seismicity (RIS) causes landslides, sedimentation, earthquakes and siltation.
5. Waterlogging and salinity due to over irrigation.
6. Due to structural defects or faulty design of the dam may cause sudden dam failure leading to collapse and destruction to life and property.