Why Did Relations Between Rome and the Byzantine Empire Deteriorate

Why did relations between Rome and the Byzantine Empire deteriorate so markedly in the late seventh and early eighth centuries?

A) Constantinople was outraged by Roman support for the Merovingian kings.
B) The Roman pontiffs believed that the Byzantine emperors had not done enough to stem the invasions of the Arabs.
C) Doctrinal issues, including the thorny question of icons, began to divide eastern and western churches.
D) The Byzantine emperor had asserted his right to appoint and dismiss bishops and cardinals.