The correct answer is the following: option A. After the Slaughterhouse Cases changed the intent of the Fourteenth Amendment, the Supreme Court used the due process clause. In 1873, the Slaughterhouse Cases became the first cases in which the Supreme Court did an interpretation of the 14th Amendment, which had been recently ratified. The Supreme Court used the due process clause, which deals with the administration of justice acting as a safeguard from arbitrary denial of life, liberty and property, done by the government outside of the sanction of a law. It became a historic ruling of the Court in civil rights, because it stated that the Fourteenth Amendment protects the immunities and privileges of citizens of the United States, and not citizens of States.