Final answer:
The lunar highlands have a higher abundance of radioactive elements compared to the maria.
Step-by-step explanation:
The lunar highlands have a higher abundance of radioactive elements compared to the maria. The highlands are the lighter, heavily cratered regions of the Moon, which are generally several kilometers higher than the maria. Typically, there are 10 times more craters on the highlands than on a similar area of maria. This suggests that the highlands have experienced more impacts over time, leading to a higher concentration of radioactive elements.