The lack of any obvious source for many outflow channels on Mars suggests that the water originated from
A) underground
B) the atmosphere in the form of rain
C) ancient melting glaciers
D) the atmosphere in the form of snow

Question

Quizplus · Accepted Answer

The lack of any obvious source for many outflow channels on Mars suggests that the water originated from underground. This is supported by evidence of subsurface ice deposits and the fact that some outflow channels are located near areas where subsurface water has been detected.

The Lack of Any Obvious Source for Many Outflow Channels