Before the Mongolian invasions, armies were intimidated when they faced an army larger in than themselves. Why did the people in neighboring regions learn to fear Genghis Khan's relatively small armies? A. Mongolian invaders traveled extremely quickly and were very highly trained and disciplined.
B. The Mongolian army used cart-like wagons to carry huge lethal cannons into battle.
C. They knew that the Mongolian army had blood thirsty leaders who enjoyed a good massacre.
D. Mongolian warriors used loud battle cries to scare their enemies' horses.

Mongolian invaders traveled extremely quickly and were very highly trained and disciplined.

Explanation:

Usually an army is worried about being overwhelmed by the sheer number of combatants they face. However, a highly mobile force like Genghis Khan’s can also cause great fear in an enemy because they have the ability to travel quickly and to strike without warning. This fact combined with the advanced skills of Mongolian warriors produced a lethal effect, and cities often surrendered without a fight when Genghis Khan showed up.

also i got it right on the exam