The longest mountain range of Middle Himalayas is

Dhauladhar
Shivalik
Pir Panjal
Burzil

The correct answer is C. Pir Panjal.

The Pir Panjal Range is a mountain range in the Himalayas that runs from the Kashmir Valley in the west to the Chamba Valley in the east. It is the longest mountain range of the Middle Himalayas, and it is a major watershed between the Indus and Ganges river basins. The Pir Panjal Range is a popular destination for trekking and mountaineering.

The Dhauladhar Range is a mountain range in the Himalayas that runs parallel to the Pir Panjal Range to the south. It is a much shorter range than the Pir Panjal, and it is not as well-known for trekking and mountaineering.

The Shivalik Range is a low mountain range that runs along the foothills of the Himalayas. It is a very young range, and it is still being formed by the collision of the Indian and Eurasian plates. The Shivalik Range is not a popular destination for trekking or mountaineering.

The Burzil Pass is a mountain pass in the Pir Panjal Range. It is a high-altitude pass, and it is only open for a few months each year. The Burzil Pass is a popular destination for trekking and mountaineering.