Final answer:
The correct inference from the Twenty-Third Amendment is that people living in Washington, DC, were not entitled to vote for President before the amendment was passed.
Step-by-step explanation:
The Twenty-Third Amendment, ratified in 1961, granted residents of Washington, DC the right to vote for the President by allowing them three votes in the Electoral College. This amendment addressed the issue that people living in Washington, DC, were not entitled to vote for the President before its passage. Therefore, the correct inference from the Twenty-Third Amendment is option a) People living in Washington, DC, were not entitled to vote for President before the amendment was passed.