The Facilities, Money, Expertise, and Resources Needed to Produce Plutonium

The facilities, money, expertise, and resources needed to produce plutonium are probably far outside the capability range of non-state actors, but how could they still become a nuclear threat?

A) Dirty bombs are a lot easier to make and have similar radioactive effects.
B) Such non-state terrorist organizations will never be a nuclear threat.
C) The theft of plutonium is a danger, as only a small amount of plutonium is needed to make a bomb.
D) All that is really necessary is the expertise, since resources are not too hard to come by. That is why terrorist groups have been radicalizing universities lately.