The correct answer is - d. mountain building.
The mountain building is a process that in its essence has the land lifting up, thus gaining on elevation. That process happens when there's two plates colliding with one another, and because of all the pressure that is between them while they push against one another, the land that has been flat, or relatively low, starts to gain on elevation, thus gradually becoming a mountain.
Perfect examples for this process are the Himalayas, the Andes, the Atlas Mountains, all of which have arose from an uplift of the land because of plate collision.
