Which of the Following Statements Is Justified by the Map

Which of the following statements is justified by the map shown here?
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A) The Sasanid Empire assumed control of the lands formerly occupied by the Muslims.
B) The western Roman Empire had largely disintegrated as a result of barbarian invasions.
C) The Byzantine Empire assumed all lands formerly controlled by the western Roman Empire.
D) The Bulgarian Khanate was a threat to the Sasanids by c. 700.