Answer:
Option: It was thought they might rebel.
Step-by-step explanation:
The African American was denied to fight at the beginning of the Civil War because the government did not trust them, and thought they might rebel against the Whites in America.
Early in history, it is seen before, the slaves fighting against their masters and giving it rise to revolt, just like in Haiti Revolution. By keeping this in mind, the American government decided to keep former slaves away from war and arms to fight.