Final answer:
The statement that Io's impact craters have been buried by lava flows is true, as Io is highly volcanically active, rapidly covering any craters that form.
Step-by-step explanation:
The statement that Io had impact craters which have all been buried in lava flows is true. Io, one of Jupiter's moons, is the most volcanically active body in the solar system. Its surface is constantly being resurfaced by volcanic activity, which covers any impact craters that may have formed. This is different from the Earth's moon, where many impact craters have been preserved because of the lack of atmosphere and geological activity. Since Io is so geologically active, any impact craters that do occur are quickly buried under lava flows, maintaining a relatively smooth surface despite the continuous bombardment by debris in the solar system.