Before the emancipation proclamation, african americans
were not allowed in the north.
were not allowed in border states.
could not join the union military.
could not join the confederate military.

It is C

Explanation: It was not until Abraham Lincoln signed the Emancipation Proclamation on January 1, 1863 that African-Americans could join the Union army. This move by Lincoln allowed for a significant increase in the amount of manpower available for the Union war effort.

C. could not join the union army

Explanation:

a big wall across the mexican border so no drugs, terrorist, or illegal immigrants can come through : )