Use the quotation to answer the question

Question

“They [the Mongols] attacked Russia, where they made great havoc, destroying cities and fortresses and slaughtering men; and they laid siege to Kiev, the capital of Russia; after they had besieged the city for a long time, they took it and put the inhabitants to death. When we were journeying through that land, we came across countless skulls and bones of dead men lying about on the ground. Kiev had been a very large and thickly populated town, but now it has been reduced almost to nothing, for there are at the present time scarce two hundred houses there and the inhabitants are kept in complete slavery. Going on from there, fighting as they went, the Tartars [Mongols] destroyed the whole of Russia.” –  Friar Giovanni da Pian del Carpine 

Based on the quotation, what are conclusions that it supports?
A. The Mongols were not successful conquerors because cities were able to outlast their sieges.
B. The Mongols were successful conquerors who treated conquered peoples with dignity.
C. The Mongols were successful conquerors who treated conquered peoples ruthlessly.
D. The Mongols were not successful conquerors because the lands they fought with became unusable.

Answer 1

C. The Mongols were successful conquerors who treated conquered peoples ruthlessly.