Well last Friday when we had the quiz , he was about to collect them , and I realized I had an addition mistake in my Gauss - Jordan , which was why my checking of the matrices did n't come out correctly . I asked him if he could pick up mine last ( I was the first one that he picks up ) because I found a simple mistake . He just told me to put " mistake " there and he will overlook it . Well he did n't .

Question: Why was someone about to collect the quizzes ?
Answer: None of the above choices .Because the quiz was over .Because I realized I had an addition mistake .Because my checking of the matrices did n't come out correctly .