What was the effect of the persian wars?

Which of these statements best describes the ambiguity in this excerpt

How did african americans the union during the civil war? a. by serving as representatives in congress b. by enlisting in the military to fight c. by organizing massive slave revolts in the south d. by negotiating for peace with the confederacy

Brainliestttme : ) what are trading blocs and what is the impact of international cooperation?