Final answer:
After the Civil War and before the 15th Amendment was ratified, the 14th Amendment had been ratified, granting citizenship and equal protection to African Americans.
Step-by-step explanation:
The question addresses the period of Reconstruction in American history, specifically between the end of the Civil War and the ratification of the 15th Amendment. The correct answer is c. The 14th Amendment was ratified. This amendment, forming one of the critical components of the Reconstruction Amendments, granted citizenship to African Americans and equal protection under the law, drastically altering the legal and social landscape of the United States. However, though the 15th Amendment, which was concerned with providing voting rights to African American men, was proposed, it had not been ratified yet, therefore, African Americans were not legally guaranteed the right to vote until its ratification in 1870.