The correct answer is - c - convergent.
The convergent boundaries are the plate boundaries where two or more tectonic plates move towards one another. Because of the high pressure that is made on the land because of the pushing against one another by the plates the land starts to lift up. The process is pretty slow, but gradually as the land lifts up more and more and gains on elevation the first signs of a hill will appear, than small mountain, and as the process continues it can end up with a very high mountain. The Himalayas are a perfect example of the results of this type of boundary.