The correct answer is:
c: Two plates of almost equal density converge and, instead of subducting under one another, they uplift into a mountain.
In the case of the Himalayas, they were formed by the collision of the Indian Plate and the Eurasian Plate, both of which are of relatively similar density. This collision caused the crust to buckle and fold, leading to the uplift of the Himalayan mountain range. This process is known as continental collision.