One of the reasons that terrorism is so effective is that it can make everyday objects or common public gatherings dangerous. Which BEST explains why this makes terrorism a difficult social problem to solve?

A.
It makes it much easier to tell terrorists from average citizens.

B.
There are few government agencies whose purpose is to fight terrorism.

C.
The tools of terrorism are very accessible to those who want to do harm.

D.
Most terrorists do not have any kind of agenda and strike random people.