What evidence do we have that there has been liquid water on Mars's surface in the recent past?
A)Small pools of surface water
B)Ice clouds in the atmosphere
C)Very young channels near the rims of craters
D)Observations of large quantities of subsurface ice

Question

Quizplus · Accepted Answer

Very young channels near the rims of craters suggest that liquid water flowed on Mars's surface in the recent past. These channels were likely carved by water flowing from underground reservoirs, which were briefly exposed by impacts that excavated the craters.

Answer: A
 Small pools of surface water have been observed in recent years on Mars's surface. These pools are thought to be formed from melting ice or from underground aquifers that occasionally release water to the surface.

Therefore, the best choices are A and C.

What Evidence Do We Have That There Has Been Liquid