The correct answer is: "fomer slaves, who mostly were represented by the African American population".
The 14th Amendment to the US Constitution was issued in 1868 during the Reconstruction period after the Civil War. It adressed the issue of guaranteeing equal rights and protection by law of former slaves. One of the rights explicitly confered were citizenship or the due process clause. The latter established that no person could be imprisoned or sanctioned legally without a fair trial.