Who or What Were Known as Contrabands During the Civil

Who or what were known as contrabands during the Civil War?

A) Confederate goods that smugglers snuck through the Union blockade in an elaborate attempt to profit off the war and bring money back into the South
B) groups of immigrants who had initially ventured west but returned to the South in large numbers because of the promise of being paid to join the army
C) thousands of slaves who showed up in Union army camps and sought protection and freedom as the war expanded, thereby helping push the issue of emancipation
D) Native American soldiers who fought for the Union in return for large swaths of land and who often served as spies in the South
E) military weapons imported to the South from Europe before Britain and France went on to officially form an alliance with the Confederacy