Answer:
D
Step-by-step explanation:
Lunar missions were strong for a few years until NASA ran out of money to support them. 
"Lunar missions were strong for a few years": NASA had success in the Apollo 11 mission, and then six other after it. They put 12 astronauts total on the moon, over the course of about 3 years. 
"NASA ran out of money to support them": The government stopped providing money to allow these missions to happen. Therefore, NASA hasn't sent anyone to the moon since 1972. 
So, choice D is correct.