The power plant at Manikaran, based on geothermal energy, is in the state of Jammu and Kashmir.

Geothermal energy is a renewable source of energy that utilizes the heat from within the Earth to generate electricity. It involves drilling deep into the Earth's crust to access hot water or steam reservoirs, which can then be used to drive turbines and produce electricity.

Manikaran is a small town located in the Parvati Valley of the Kullu district in the Indian state of Himachal Pradesh. It is famous for its hot springs and is considered a sacred place by both Hindus and Sikhs. However, there is no geothermal power plant in Manikaran.

The correct answer to the question is option 'C' - Jammu and Kashmir. Jammu and Kashmir is a union territory in northern India, bordered by Himachal Pradesh and Punjab to the south. It is known for its scenic beauty, including the Himalayan mountain range and the famous Dal Lake.

In Jammu and Kashmir, the power plant at Manikaran is based on geothermal energy. This power plant utilizes the natural hot springs in the region to generate electricity. The hot water from the springs is used to produce steam, which is then used to drive turbines and generate electricity. This is a sustainable and environmentally friendly way to produce power.

The geothermal power plant at Manikaran in Jammu and Kashmir plays a significant role in meeting the energy needs of the region. It helps in reducing the dependence on conventional sources of energy and contributes to a greener and more sustainable future.

In conclusion, the power plant at Manikaran, based on geothermal energy, is located in the state of Jammu and Kashmir.