By the Ninth Century, What Happened to the Abbasid Control

By the ninth century, what happened to the Abbasid control of the empire?

A) The Abbasids continued to develop absolutism in such a fashion that they controlled a large portion of Eurasia.
B) Non-Arab peoples, particularly the Turks who had converted to Islam, increasingly dominated political life.
C) Successive defeats of the Abbasids by the Byzantine empire led to the collapse of the dynasty and the emergence of a Greek hegemony.
D) Eventually the Persian influence in the Abbasid empire resulted in the removal of the capital to Merv and the rise of a purely Persian dynasty.