The correct answer is (b), Pithoragarh.
Koteshwar cave is a Hindu cave temple dedicated to Lord Shiva. It is located in the Pithoragarh district of Uttarakhand, India. The cave is about 100 kilometers from the city of Pithoragarh and is situated at an altitude of about 2,500 meters. The cave is believed to have been built in the 11th century by the Katyuri kings. The cave is a popular tourist destination and is known for its beautiful sculptures and paintings.
The other options are incorrect.
(a) Dehradun is the capital of Uttarakhand. It is located in the Garhwal region of the state.
(c) Rudraprayag is a town in the Rudraprayag district of Uttarakhand. It is located on the banks of the Alaknanda River.
(d) Almora is a town in the Almora district of Uttarakhand. It is located in the Kumaon region of the state.