The correct answer is: "D"
On February 27, 380, Christianity became the exclusive religion of the Roman Empire by a decree of Emperor Theodosius, which had far-reaching consequences.
The decree united the Judeo-Christian roots of the European continent with the Greco-Roman culture. Until the Council of Nicea, in the year 325, the Christian churches were burned down, those who professed the Christian religion were persecuted and their patrimony was confiscated. Particularly under the emperor Diocletian (245-316) Christian persecution intensified. Diocletian wanted to revive the old pagan cults and that these became the religion of the empire. But his anti-Christian policy failed and was eliminated by his successor, Emperor Constantine (285-337).
The military and administrative apparatus worked well in the Roman Empire. A free trade zone had boosted economic welfare. The inhabitants of Rome enjoyed civil rights, which promoted a growing cohesion among the population, however, there was no religious freedom.
For the practitioners of the Christian religion the situation improved. On February 27, 380, the Roman emperor of the East Theodosius (347-395) signed, in the presence of the Western Roman emperor Valentinian (371-392) and his co-ruler half-brother Gratian (359-383) a decree with the who declared Christianity the religion of the State and stipulated a punishment to those who practiced pagan cults. The decree "Cunctos populos" granted not only a preponderant place to Christianity, but also implied persecution against those who practiced another faith.