Recent Research Has Suggested That the Moon's Surface Might Be

Recent research has suggested that the Moon's surface might be hazardous to astronauts because:

A) the crater walls are unstable and liable to collapse if disturbed.
B) the regolith is much deeper than previously thought, and an astronaut might easily sink into it.
C) the tiny regolith particles may cause serious lung problems.
D) moonquakes are more severe than previously suspected.