The correct answer is Lahaul and Spiti.
Lahaul and Spiti is the largest district in Himachal Pradesh, India, with an area of 13,835 square kilometers (5,336 sq mi). It is located in the north-eastern part of the state, bordering Ladakh to the north, Kinnaur to the south, and Spiti to the east. The district is divided into two sub-divisions, Lahaul and Spiti.
Lahaul is a valley located in the upper reaches of the Chenab River. It is a cold desert region with a high altitude and low rainfall. The main towns in Lahaul are Keylong, Jispa, and Tandi.
Spiti is a valley located in the upper reaches of the Spiti River. It is a cold desert region with a high altitude and low rainfall. The main towns in Spiti are Kaza, Tabo, and Dhankar.
The district is home to a number of Buddhist monasteries, including the Tabo Monastery, which is one of the oldest monasteries in the world. The district is also home to a number of Hindu temples, including the Hadimba Temple in Mandi.
The district is a popular tourist destination, with a number of trekking and mountaineering routes. The district is also home to a number of wildlife sanctuaries, including the Pin Valley National Park and the Hemis National Park.