问白勇一道题：A和C有什么区别，多谢

2. In the late seventh century, in a dispute over whether the Prophet Muhammad's son-in-law, Ali, should carry on as the fourth caliph, Muhammad's successor, Islam split into two branches, the Sunnis and the Shiites.

(A) over whether the Prophet Muhammad's son-in-law, Ali, should carry on as the fourth caliph, Muhammad's successor

(B) over if Ali, the Prophet Muhammad's son-in-law, was going to carry on and be the fourth caliph, Muhammad's successor

(C) over whether Ali, the Prophet Muhammad's son-in-law, was going to carry on and be the fourth caliph, Muhammad's successor

(D) as to whether the fourth caliph, Muhammad's successor, is to be the Prophet Muhammad's son-in-low, Ali

(E) concerning if the fourth caliph, Muhammad's successor, was to be the Prophet Muhammad's son-in-law, Ali

answer A, why not C?