We suspect that Mars once had liquid water on its surface because:
A) mapping satellites have detected dry river beds
B) rovers have detected minerals that must have formed in the presence of liquid water
C) mapping satellites have detected outflow channels coming from impact craters
D) all of the above

Question

Quizplus · Accepted Answer

Mapping satellites have detected dry river beds and outflow channels coming from impact craters, and rovers have detected minerals that must have formed in the presence of liquid water. These pieces of evidence suggest that Mars once had liquid water on its surface.

We Suspect That Mars Once Had Liquid Water on Its