Question

4
which of the following is a discovery that supports the theory that there was once, or may still be, liquid water on planet earth?
a. there are large ponds and lakes present on the surface of mars.
b. there are river-like channels and rocks with an eroded appearance on mars.
c. life is present on saturn and mars, so therefore water must exist on those planets.
d. jupiter experiences daily rainfall and has several small rivers.

Explanation:

• Option A is incorrect because Mars currently has no large surface ponds/lakes; its surface water would evaporate due to low atmospheric pressure.
• Option B is correct: River-like channels and eroded rocks are geological features that form from sustained liquid water flow, which is key evidence for past (or potentially present subsurface) liquid water on Mars.
• Option C is incorrect because there is no confirmed life on Saturn or Mars.
• Option D is incorrect: Jupiter is a gas giant with no solid surface, so it cannot have rivers or rainfall as we know it on rocky planets.

Answer:

B. There are river-like channels and rocks with an eroded appearance on Mars.