The correct answer is; "What proof the tripster is able to provide".
That´s because as a reporter, he must make sure about the authenticity of the accusation as he cannot post apocryphal news.
This quote can be found only in the movie.
It can be heard in the third movie, and is told by the headmaster.
I just checked the book, and it doesn't appear there.
I am so sorry but I don't understand the question that you had asked.
