The Mongols had the advantage of gunpowder weapons, therefore A seems to be the most logical answer.
The soviet union rejected the Marshall Plan and forbid any of 'their' contries (the eastern European ones) from accepting any of the much needed help because the USA and the Soviet Union were, at the end of the day, enemies. Those countries simply never saw a single penny.
If you are thinking of the ships from Africa, the ships conditions were horrible, there was a lot of deaths on the ships with the slaves, it was rare to have the ships with slaves to have 80%+