Please help! ;( How were slaves and the the Union war effort helped by Union control of large areas of Louisiana during the war?

A) Slaves were hired by the Union from plantation owners and put to work in the Union Army.

B) Slaves were freed because plantation owners traded them to the Union Army in exchange for resources and permission to keep their plantation.

C) Escaped slaves guarded large areas of Louisiana and protected Union soldiers from Confederate attacks.

D) Many slaves were able to escape and join the Union war efforts against the South.