What Was the Most Significant Impact of the Period of the Mongol

What was the most significant impact of the period of the Mongol rule on Russia?

A) The period of Mongol rule reinforced the isolation of Russia from western Europe and the developments of the Renaissance and Reformation.
B) The Mongols aided the Russians in gaining political dominance over the peoples of the Asiatic steppes.
C) The period of Mongol rule introduced many Islamic people into the region of Russia.
D) The Mongol domination resulted in the destruction of Eastern Orthodoxy and the rise of Nestorian Christianity.