What Was the Attitude of the Imperial Administration to Local

What was the attitude of the imperial administration to local governments within the empire?

A) Local governments were replaced by military garrisons directly responsive to the central government
B) Local governments were replaced by professional bureaucrats formally trained at imperial universities.
C) Local governments were handed over to relatives of the imperial family who ruled as vassals of the empire.
D) Local governments were granted considerable autonomy, and in some cases whole kingdoms were preserved.