Final answer:
The Thirteenth Amendment, ratified shortly after the Civil War, officially abolished slavery in the United States and gave Congress the authority to enforce this abolition. The correct option is (A).
Step-by-step explanation:
As a result of the Civil War, the institution of slavery was officially abolished through the ratification of the Thirteenth Amendment to the United States Constitution.
This pivotal amendment was passed by Congress on January 31, 1865, and by the end of that year, had received the necessary approval from three-fourths of the states, ensuring that four million people were emancipated after 250 years of slavery in North America. Section Two of this amendment granted Congress the power to enforce the abolition of slavery with appropriate legislation.
The Thirteenth Amendment states that "neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction."
Notably, the Emancipation Proclamation had only freed enslaved people in rebellious states, leaving many in bondage, particularly in border states. The Thirteenth Amendment rectified this by permanently banning the practice of slavery across the entire nation.