A.
To point out the dangers inherent in mining for helium-3 on the Moon
B.
To point out a flaw in the theory that helium-3 can be found on the Moon's surface
C.
To explain why it was difficult for astronauts to detect helium-3 on the Moon
D.
To explain why it is likely that there are large amounts of helium-3 on the Moon
正确答案:D