The correct answer is (a) Uttarkashi.
Nanda Devi National Park is a national park in the Garhwal Himalayas of Uttarakhand, India. It is the largest national park in India and is home to a variety of wildlife, including snow leopards, Himalayan tahr, and musk deer. The park is also home to the Nanda Devi peak, which is the second-highest peak in India.
The park was established in 1982 and is a UNESCO World Heritage Site. It is a popular tourist destination and offers a variety of activities, including trekking, mountaineering, and camping.
The other options are incorrect because:
(b) Tehri is a district in Uttarakhand, India. It is located in the Garhwal Himalayas and is home to the Tehri Dam, which is the largest dam in India.
(c) Chamoli is a district in Uttarakhand, India. It is located in the Garhwal Himalayas and is home to the Kedarnath Temple, which is one of the most important Hindu temples in India.
(d) Champawat is a district in Uttarakhand, India. It is located in the Kumaon Himalayas and is home to the Jim Corbett National Park, which is the oldest national park in India.