Diocletian Created the Dominate and a Tetrarchy That Divided the Empire

Diocletian created the dominate and a tetrarchy that divided the empire into four parts because

A) one ruler could not defend the entire empire.
B) government had become too expensive.
C) the bureaucracy had grown too large.
D) the army had too little influence in politics.
E) Roman political structure should mirror the Christian church organization.