Question

Which of the following Byzantine contributions formed the basis for much of medieval European law? Separation of church and state The Justinian Code The Hagia Sophia Polemon

Answer 1

Separation of Church and State is and Enlightenment era idea, much later than the Byzantines.
Polemon could be a Japanese game but it's not. It's the name of several Greek guys, a philosopher, a king and that sort of guy. But they all lived in the 4th century BC or earlier.
Hagia Sophia is a great building built by the Byzantines, used as a stable by the Janissary when the finally took Constantinople and is now a mosque in Istanbul. It's Byzantine, but doesn't have much to do with law.
So that leaves.... Code, in law, means an organized list of laws. So that could be it. Justinian was a great Byzantine leader. So I'm thinkin' we've got your answer.