Answer:
c. Hagia Sophia, Istanbul.
Step-by-step explanation:
The Hagia Sophia Grand Mosque in Istanbul, Turkey was built in 537 during the imperial rule of Constantinople, now known as Istanbul. This architectural structure was the largest Christian Church during the early Roman empire.
This monument was built during the reign of the Byzantine emperor Justinian I. It stands as one of the greatest examples of Byzantine architecture.
Thus, the correct answer is option c.