On Its Icy Surface, Uranus's Satellite Ariel Has Smooth Valleys

Multiple Choice

On its icy surface, Uranus's satellite Ariel has smooth valleys with few craters. Other areas are rough with many craters. Based on this, it can be concluded that

A) valleys are young and the rough areas are old.
B) the valleys are old and the rough areas are young.
C) both valleys and rough areas are young.
D) both valleys and rough areas are old.