C is the correct answer, but all of the other answers are close to true as well.
Answer:
the red scare was a mass hysteria when people felt threatened by communism due to the cold War between the Soviet Union and the U.S. the first red scare was in the 1920s because of the Russian revolution that had just happened and the citizens of the U.S were scared that their country would too turn to a communist government.
The Pax Mongolica brought a period of stability among the people who lived in the conquered territory. The resulting stability brought by Mongol rule opened these ancient trade routes to a largely undisturbed exchange of goods between peoples from Europe to East Asia.