The correct answer is A. July 20, 1969.
On July 20, 1969, at 20:17 UTC, Apollo 11 commander Neil Armstrong and lunar module pilot Buzz Aldrin became the first two humans to land on the Moon. They spent two and a half hours outside the spacecraft, conducting scientific experiments and collecting samples. Armstrong and Aldrin returned to the command module, piloted by Michael Collins, and the three astronauts returned to Earth on July 24.
Option B is incorrect because it is the date that Apollo 11 landed on the Moon. Option C is incorrect because it is the date that President John F. Kennedy announced the goal of landing a man on the Moon and returning him safely to Earth by the end of the decade. Option D is incorrect because it is the date that Apollo 12 landed on the Moon.