The first one, A, makes the most sense.
During the Cold War, the United States remained a democratic republic with a capitalistic economic system. Whereas the USSR, was a communist nation with a dictatorship. Until Stalin dies, the country is not holding elections however after the USSR will move more toward an election process. However, the government owned all means of production as a socialist economy.
However, following from time, Vietnamese nationalism also changed and through it, it also focused on only one goal - independence of Vietnam. After 1979 war with China, Vietnam nationalism became anti-China. The sentiment grows bigger because of South China Sea/Vietnam East Sea dispute.
I think
The answer is interracial schools. School segregation in the US started in its de jure form with the passage of Jim Crow laws in the late 19th century. It is affected by the history of southern states as patterns of residential segregation, slave societies, and later school selection programs, and Supreme Court rulings about past school desegregation efforts.