Once the Christian Church Gained Ascendancy in the Roman Empire,the

Once the Christian Church gained ascendancy in the Roman Empire,the highest authority in deciding doctrine was:

A) the Bishop of Rome,who was the pope.
B) the emperor,as a newly styled pontifex maximus of the Christian Church.
C) the Christian leader of Christianity's holiest city,the Patriarch of Jerusalem.
D) the leader of the church in Constantinople,the Patriarch of Constantinople.
E) the Christian believers.