Why might transition zones be areas of conflict?

Transition zones may be areas of conflict because very often the people that want to transit through some country in the goal to get to the wished destination get stuck in some of the transition countries. When this happens, from multiple causes, thy are not allowed to go further, and their only option is to either go back (but occasionally even that is not an option), or wait. This leads the people that transit to feel unpleasant and restricted, so they often try to solve that in violent way or by trespassing the borders, and they also make damage to the local inhabitants, so the answer from the locals is also aggressive because they feel and are endangered, thus a fertile soil for conflict comes on the scene.  

The answer is a but it also might be 7 so