Answer:
D. The Abbasid state was headed by a caliph who was theoretically the state's supreme religious and political leader.
Explanation:
Caliphs concentrated in their hands religious and political power. The Abbasid caliphs, who reproached their Umayyad predecessors for behaving like secular rulers, tried to outline their own approach to government in Islamic terms and, accordingly, to the extent that they managed, they tried to adhere to a religious orientation in politics.