Although the Glory of Rome Faded as the Early Middle

Although the glory of Rome faded as the early Middle Ages settled over western Europe, philosophy survived in Byzantium for another thousand years or so because

A) Persians invaded the Byzantium.
B) the Greek language predominated there, making it easy for the Byzantines to continue the study of Western philosophy.
C) Natives from Greece settled in Byzantium.
D) The Romans passed over the legacy of philosophy to the Byzantines.