The correct answer is option 3: large scale folding. The Himalayan mountain ranges were formed as a result of the collision between tectonic plates. The Indian plate, which was originally located south of the Eurasian plate, started moving northward and collided with the Eurasian plate.

During this collision, the layers of rocks in the Earth`s crust were subjected to immense pressure and were folded upwards, creating the towering peaks of the Himalayas. This process of folding is known as large scale folding.

Option 1, differential erosion, refers to the uneven erosion of different layers of rocks. While erosion may have played a role in shaping the Himalayas, it is not the primary cause of their formation.

Option 2, faulting of crustal blocks, refers to the movement of blocks of crust along faults. While faulting can occur in mountain building processes, it is not the main process responsible for the formation of the Himalayas.

Option 4, volcanic eruption, involves the release of molten rock, ash, and gases from the Earth`s interior. While volcanic activity can contribute to the formation of certain mountain ranges, such as the Andes in South America, it is not the mechanism responsible for the formation of the Himalayas.

Therefore, the correct