C. Agriculture
Is what they where most successful in
During WWll, with white men fighting overseas, African Americans were able to get better job opportunities, and a new law passed saying that blacks and whites had to be in integrated units in the army. But, when the war ended and black soldiers returned to America they weren't greeted with a hero's welcome and instead were treated like all other blacks- they were forced to be segregated. This change from almost equality to none at all really fired up the Civil Rights Movement in the 1950's and 1960's.
Because of their knowledge of how to hide, and confuse other people when they are fighting in a jungle or something, the guerill force would have the element of suprise when fighting a larger force.
The Korean war had a purpose but it had largely failed.
Explanation:
Truman can and cannot be blamed for the war as he had formulated this policy of attacking in per preemptive measures to control the spread of communism that had plagued the US for so long.
At the same time the nature of the policy was such that it has led to the development of the US in certain senses.
So, as all things in history it is a two way thing and often based around the perspective one has of things.
The war itself was not a success in terms of containing communism as North Korea was out of grasp.