Answer: G. The addition of Hiram Rhodes Revels to the U.S. Senate
Explanation:
Hiram Rhodes Revels was the first black Senator in the United States and he represented Mississippi. On the day he was to be seated in the Senate, Southern Democrats opposed his seating thus prompting a debate that ended in a vote.
In this debate, Charles Sumner, a known anti-slavery Republican, uttered those words to reflect that the time had finally come to treat African Americans as equal as the Constitution intended.
