(mc)which of these contributed to increasing tensions between the united states and the communist world at the beginning of the cold war period?

The correct answer to this open question is the following.

The situations that contributed to increasing tensions between the United States and the Communist world at the beginning of the Cold War period were the following: the arms race, the Cuban missile crisis, the space race exploration and the sending of the first man to space, and the USSR occupied nations in Eastern Europe.

Since the beginning of the Cold War, the Soviet Union and the United States lived in permanent confrontation. The USSR tried to spread Communist in many places and the United States tried to stop it. The Soviet Union supported North Korea and North Vietnam, while the US supported South Korea and South Vietnam. The arms race put the world on the brink of another war with the critical moments of the Cuban missile crisis.  

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.

c or d both can be the answer