The correct answer is: d) Residual mountains.
Residual mountains are formed when the land is uplifted and the softer rocks are eroded away, leaving behind the harder rocks. The Shivalik Hills in Punjab are an example of residual mountains. They are formed from the hard rocks of the Siwalik Group, which are resistant to erosion. The softer rocks that were once around the Siwalik Group have been eroded away, leaving the Shivalik Hills standing alone.
Fold mountains are formed when two tectonic plates collide and the rocks are folded and faulted. Volcanic mountains are formed when magma erupts from a volcano and cools to form rocks. Block mountains are formed when the land is uplifted and the blocks of land are tilted or faulted.