Why Did the Westward Expansion of the Mongol Empire End

Multiple Choice

Why did the westward expansion of the Mongol empire end after 1241?

A) The Mongol armies were defeated by the Germans at the battle of Liegnitz.
B) The Mongol armies were defeated by the Hungarians at the River Sajo.
C) The Mongol empire split up into hostile factions.
D) The internal supply lines for the Mongol army became overextended,forcing the army to retreat.
E) The Mongol empire was assimilated into the Byzantine empire peacefully.