The correct answer is: D. Lahaul and Spiti
Lahaul and Spiti is a district in the Indian state of Himachal Pradesh. It is the largest district in Himachal Pradesh by area, and the least populous. The district is located in the eastern part of the state, and is bordered by Tibet to the north, Kinnaur district to the south, Chamba district to the west, and Spiti district to the east. The district is divided into two sub-divisions: Lahaul and Spiti.
The district is a high-altitude region, with an average elevation of over 3,000 meters (10,000 feet). The climate is cold and dry, with an average temperature of 5 degrees Celsius (41 degrees Fahrenheit). The district is home to a number of glaciers, including the Chandrabhaga Glacier, the largest glacier in Himachal Pradesh.
The district is a popular tourist destination, known for its natural beauty, including its mountains, glaciers, and lakes. The district is also home to a number of Buddhist monasteries, including the Tabo Monastery, the oldest monastery in the Spiti Valley.
The district is also home to a number of tribal communities, including the Lahaulis and the Spitis. The Lahaulis are a Hindu community, while the Spitis are a Buddhist community. The two communities have a long history of interaction and cooperation.
The district is a beautiful and remote region, with a rich history and culture. The district is a popular tourist destination, and is home to a number of Buddhist monasteries. The district is also home to a number of tribal communities.