The correct answer is: A. Zanskar
Spiti and Kinnaur are separated from Tibet by the Zanskar Range, a mountain range in the Indian state of Himachal Pradesh. The Zanskar Range is a sub-range of the Himalayas, and it is located to the north of the Spiti Valley and the Kinnaur Valley. The Zanskar Range is a high mountain range, with peaks reaching over 6,000 meters (20,000 feet). The Zanskar Range is a major barrier between Spiti and Kinnaur and Tibet, and it is a popular destination for trekking and mountaineering.
The other options are incorrect because:
- Pir Panjal is a mountain range in the Indian states of Jammu and Kashmir and Himachal Pradesh. It is located to the south of the Zanskar Range, and it does not separate Spiti and Kinnaur from Tibet.
- Churdhar is a mountain in the Indian state of Himachal Pradesh. It is located to the south of the Zanskar Range, and it does not separate Spiti and Kinnaur from Tibet.
- Dhauladhar is a mountain range in the Indian state of Himachal Pradesh. It is located to the south of the Zanskar Range, and it does not separate Spiti and Kinnaur from Tibet.