The best description of how the Fourteenth Amendment extended and limited civil rights to Black Americans is:
The Fourteenth Amendment defined citizenship in the U.S., made all citizens equal before the law, and guaranteed due process to all citizens; however, it did not extend voting rights to Black Americans or prevent the separate but equal doctrine.
This answer reflects the key features of the Fourteenth Amendment, such as defining citizenship and ensuring equal protection and due process, while also acknowledging its limitations regarding voting rights and the subsequent endorsement of the separate but equal doctrine in Plessy v. Ferguson (1896).