The correct answer is C) The United States outlawed slavery.
The "Era of Good Feelings"refers to the era of the Monroe Presidency which took place from 1817-1825. However, the United States is not going to outlaw the institution of slavery until the passing of the 13th amendment. The 13th amendment is not passed until 1865, showing that C must be the answer, as it happened several decades after the "Era of Good Feelings."