The correct option is C Rehabilitation of people.
Following are the advantages of hydel power generation.
1. Pollution is rarely created.
2. Reduces greenhouse emissions.
3. Relatively low maintenance costs.
4. It is renewable.
Hydel power generation also poses few disadvantages as:
1.Environmental consequences due to damming of water.
2. Rehabilitation of people from the area of the dam.
3. Building dams is expensive.