Answer:
D. Christians
Step-by-step explanation:
Constantine the Great was a Roman emperor from 306 to 337 AD. Prior to his rule, Christians in Rome were persecuted, especially by the evil Emperor Nero, who blamed them for the Great Fire of Rome. One of the most notorious acts against Christians was the Great Persecution, which saw the torture of Christians, burning of Christian buildings and books, and deaths of many all around.
When Constantine ascended the throne, however, all that changed. He began to convert the citizens of the Roman Empire to accept Christianity. Historians and scientists still don't know why exactly he decided to do it, but in the end, he was successful, and Christianity spread throughout the empire.
The answer is thus D.