David didn’t pass the GCSE examination, so he wasn’t allowed to take the entrance examination to the university.

A. If David passed the GCSE examination, he would have been allowed to take the entrance examination to the university.

B. If David had passed the GCSE examination, he would be allowed to take the entrance examination to the university.

C. If David had passed the GCSE examination, he would have been allowed to take the entrance examination to the university.

D. If David had passed the GCSE examination, he would have allowed to take the entrance examination to the university.