At which altitude trees and shrubs disappear and the mountains assume a rugged, wind swept and frost bitten character in Himachal Pradesh?

The correct answer is: Beyond 4500 m.

The reason for this is that the tree line in Himachal Pradesh is at an altitude of around 4500 m. This means that above this altitude, trees and shrubs cannot grow due to the harsh conditions. The mountains above 4500 m are therefore rugged, wind swept and frost bitten.

Option A is incorrect because the tree line in Himachal Pradesh is at an altitude of around 4500 m, not 3500 m.

Option B is incorrect because the tree line in Himachal Pradesh is at an altitude of around 4500 m, not 6000 m.

Option C is incorrect because the tree line in Himachal Pradesh is at an altitude of around 4500 m, not 7000 m.