The answer is A on edge. It violated the establishment clause because it held a school function at a denominational church, which demonstrates support for a specific religion.
The answer you looking for would be A Damascus to Caesarea.
(A) He may have acted alone, although Austria-Hungary thought he was helped along by the Serbian government. ... (C) He was probably assisted by the Serbian government, which hoped that his actions would spark a world war and help Serbia gain independence.