Answer:
The newly chosen Byzantine emperor
Explanation:
The main reason for the decline of the Byzantine empire were the "civil wars" that occurred such as revolutions against the newly chosen Byzantine emperors. Such uprisings made the country weak and even fragile as it also faced war during the Arab conquests.
One main example of this was "Andronikos" who overthrew the 11-year-old Alexios. He used ruthless measures to help him with his regime. He made violence as a norm and he terrorized the people. Later on the central government's defense as well as machinery collapsed.
So, this explains the anwer.
