The evacuation of the American troops from Vietnam and practically losing the war with this Southeast Asian country had only bad effects on the United States:
- It should the world that they are not unbeatable, and that they actually lost a war with a significantly weaker opponent.
- They were a laughing stock for most of the world because of the lost war and it affected their military reputation badly.
- Inside the Untied states people were extremely angry at the loss of the war, especially because big portion of them considered it as unnecessary and without any point even before it starts.
It allowed any State decide wether or not to allow slavery not depending on their location on a map.
It included liberals and unionist in its meaning of "un-American". The House Un-American Activities Committee (HUAC) was made in 1938 to examine charged traitorousness and subversive exercises with respect to private natives, open workers, and those associations associated with having Communist ties.
A and C can work and D is partially true I would go with a or d tho