Correct Answer: (a) Koyna dam
Note: The Koyna Dam is built across the Koyna River in the state of Maharashtra. Koyna River originates in Mahabaleshwar hills. The location of other dams is as follows:
Bisalpur Dam -Rajasthan (Banas River)
Almatti Dam - Karnataka (Krishna River)
Mettur Dam - Tamil Nadu (Kaveri River)