The impact of constantine's establishment of the new rome and his declaration of christianity as legal

Constantine's actions established Christianity as a powerful force within the Roman Empire, both in Western Europe, led from Rome, and in Eastern Europe from the new capital city.

Constantine's own conversion to Christianity, and his subsequent legalization of the Christian religion, legitimized the Christian faith as the accepted religious path, favored in the empire.   Constantine sought to unify the empire under Christian faith agreement, calling for the Council of Nicea to meet near Constantinople in 325 AD (which produced the Nicene Creed).  Also, Constantine's move of the capital to "New Rome" (Constantinople) left the Bishop of Rome as the strongest leadership figure in Rome itself, which enabled the development of the power of the papacy.

the answer is option a.

these civilizations were located around fertile rivers, where they could produce an abundance of crops