Answer:
The correct answer is C: the perpetrators were responding to the U.S. harboring nation's deposed shah for medical treatment.
Step-by-step explanation:
Iran had just gone through the Islamic Revolution (1978-1979) when they overthrew the Pahlav monarchy. This revolution was made by, among other groups, revolutionary students who opposed the U.S. presence and influence on Iran's political life.
When the U.S. allowed the overthrew monarch in its territory for medical treatment these students saw it as another American move on Iranian politics. The ex-monarch the U.S. was receiving in 1979 had been put in power on Iran through a coup in 1953 that had American support.