The astronauts' footprints on the Moon will remain there for millions of years.
Why it is true
Since there is no atmosphere, wind, or water on the Moon, there is no erosion to erase the marks left by the Apollo missions, preserving them almost intact forever.
Source: Lunar Archive
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.