which statement best describes how african americans in the south contributed to the union war effort

African Americans staged work slowdowns.

Explanation:

they staged work slowdowns to negotiate some of the terms of their labor since their freedom was denied by law, Slaves used this to go against contest the rules of slaveholders and to assert their right to control their own lives

African american soldiers served in artillery and infantry and performed all noncombat support functions that sustain an army, as well. Black carpenters, chaplains, cooks, guards, laborers, nurses, scouts, spies, steamboat pilots, surgeons, and teamsters also contributed to the war cause.