The correct answer is: C. Christianity became the new major religion of the empire.
The spread of Christianity significantly changed Roman society, especially after it became more accepted within the empire. The Edict of Milan, issued in 313 AD by Emperor Constantine, granted religious tolerance to Christians and allowed them to practice their faith openly, eventually leading to Christianity becoming the dominant religion in the Roman Empire. Over time, this shift led to profound changes in societal values, institutions, and the political landscape of Rome.