Ivan II (Also Called the Great or the Terrible)'s Main

Ivan II (also called the Great or the Terrible) 's main contribution to Russian state-building was the

A) end of Mongol rule and the unification of northern Russia under the control of Moscow.
B) development of Kiev as a magnificent political and cultural center.
C) decision to make Greek Orthodoxy the national religion.
D) foundation of Russian universities similar to European institutions.