The first time Americans that were undeniably the target of international terrorism occurred in:
a. 1988, with the bombing of Pan-Am flight 103 over Lockerbie, Scotland.
b. 1993, with the bombing of the World Trade Center.
c. 1997, with the bombing in Oklahoma City.
d. 1996, with the truck bomb attack on U.S. military barracks in Dhahran, Saudi Arabia.