The Idukki Dam is one of the largest:

Thermal power plants
Hydel projects
Solar power plants
Wind energy farms Answer: b

The correct answer is b) Hydel projects.

A hydel project is a type of hydroelectric power plant that uses the gravitational potential energy of water in a reservoir to generate electricity. The Idukki Dam is a large hydel project located in the Idukki district of Kerala, India. It is the largest dam in India in terms of installed capacity, and the second largest dam in India in terms of height. The dam was constructed between 1961 and 1974, and it was commissioned in 1975. The dam is a major source of hydroelectric power for Kerala, and it also provides irrigation and drinking water to the state.

The other options are incorrect.

  • Thermal power plants are power plants that generate electricity by burning fossil fuels such as coal, oil, or natural gas.
  • Solar power plants are power plants that generate electricity by converting sunlight into electricity.
  • Wind energy farms are farms that generate electricity by using wind turbines to convert the kinetic energy of the wind into electricity.