Answer:
The good choice is:
d. the systematic codification of Roman law
Step-by-step explanation:
The Roman emperor of the East, Justinian the Great (527-565) left an impressive legacy. He reconquered lost parts of the empire in the West of Europe, he ordered a thorough codification of Roman law and was responsible for the contruction of big architectural works, including the magnificent Hagia Sophia cathedral in Byzantium. The cathedral was converted into a mosque by the Turks after the fall of Constantinopole in 1453, and after his death, other emperors lost the recovered territories in Europe. But the most enduring part of his legacy is the legal code known as the Codex Justinianus (Code of Justinian), a codification of Roman law.