Answer: A. Loss of the Balkan provinces to the Slavs
Explanation: The Balkans, once part of the Great Roman Empire, after the division into the Western and Eastern Empires, belonged to the Eastern Roman Empire, i.e. Byzantium. Byzantium had a political influence over this region for a long time, and with the gradual organization of the Slavs in several countries, attempts to exercise religious influence by Byzantium in this region began. In this way, Byzantium through various religious influences made various alliances with the Slavic rulers in the Balkans, but by the end of the 11th century this influence declined due to the strengthening of the Slovenian states, principalities, regions, etc. The Slavs also formed other alliances with the surrounding tribes as well as with religious representatives from Rome in order to strengthen their independence from Byzantium.
