Sentence Correction

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


The OA is [/spoiler]A but i went for [spoiler]C

Thanks[/spoiler]