Which of the following observations indicates that conditions on Mars may have been suitable for life in the past?
A) There are very large extinct volcanoes on Mars.
B) There is a very deep and long canyon that extends across Mars.
C) There are dried-up riverbeds on Mars.
D) Mars has polar caps made of "dry ice."
E) Mars has two small moons.

Question

Quizplus · Accepted Answer

The presence of dried-up riverbeds on Mars suggests that liquid water, a key ingredient for life, may have flowed on the planet in the past.

Which of the Following Observations Indicates That Conditions on Mars