Correct Answer:
D. John F. Kennedy
The age at which a president assumes office is a notable historical detail. While Theodore Roosevelt was younger when he *succeeded* to the presidency, the question specifically asks for the youngest *elected* president, referring to the age at inauguration after winning an election.
- D: John F. Kennedy holds the distinction of being the youngest person ever *elected* to the U.S. presidency. He was inaugurated on January 20, 1961, at the age of 43.
- A: James Monroe was 58 when he became president.
- B: Abraham Lincoln was 52 when he took office.
- C: Herbert Hoover was 54 at his inauguration. These individuals were all significantly older than Kennedy when they assumed the presidency after being elected.