The correct answer is: d) All of the above.
The development of hydropower projects in Sikkim needs to carefully consider environmental impacts, social displacement, and geological risks.
Environmental impacts: Hydropower projects can have a significant impact on the environment, including the loss of biodiversity, the disruption of river flows, and the generation of greenhouse gases.
Social displacement: The construction of hydropower projects can also lead to social displacement, as people are forced to relocate from their homes and land.
Geological risks: Hydropower projects can also be vulnerable to geological risks, such as earthquakes and landslides.
It is important to carefully consider all of these factors before developing hydropower projects in Sikkim.