Previous to 9/11, How Was Terrorism Executed

Previous to 9/11, how was terrorism executed?

A) Terrorism was random, occurred mostly overseas, was infrequent and if it happened an agency would respond, and justice would be served.
B) Terrorism previous to 9/11 was mostly from separatist movements such as the IRA because religious terror had not yet come into existence.
C) Terrorism was executed by a few consistent groups, but it was nothing compared to the scaling threat of terrorism that we now face.
D) Acts of terror were committed against other Western civilizations that were closer to the Middle East.