Read the excerpt from Moon Mission.

People first set foot on the moon on July 20, 1969. Astronauts Neil Armstrong and Buzz Aldrin stepped from the Apollo 11 spacecraft and planted an American flag on the moon’s rocky surface. Six NASA lunar missions followed over the next few years, and 10 more astronauts walked the lunar surface. Then the United States government stopped funding such missions. NASA hasn’t sent a crew to the moon since 1972.

Which central idea is best supported by the excerpt details?

The United States government was afraid to try to send people into space.
NASA determined it was less expensive to send satellites to the moon instead of people.
America marked possession of the territory of the moon by placing an American flag there.
Lunar missions were strong for a few years until NASA ran out of money to support them.