If more than one answer is recived i will choose a brainliest !

a principal who leads a prayer at a graduation violates the first amendment's

a) establishment clause
b) freedom of religion clause
c) free-exercise clause
d) lemon test clause

The answer to this question is most likely B - Freedom of religion clause. This is due to the fact that by leading a prayer at a graduation, the principal as a figure of authority is putting pressure on those graduating to participate in a prayer with him even though they may not necessarily believe in the God the prayer is addressed to.

The actual answer is establishment clause  

Congressional approval.