The most accurate answer regarding how Roman society was changed by the spread of Christianity is:
A. Christianity became the new major religion of the empire.
This option correctly reflects the significant transformation within Roman society, as Christianity eventually became the dominant religion of the Roman Empire, particularly after Emperor Constantine's Edict of Milan in 313 AD, which granted religious tolerance to Christians. While the other options touch on various aspects of religious change and cultural interaction, A best captures the overarching impact of Christianity on Roman society.