Question

Several pieces of evidence suggest that water was once abundant on Mars. Which of the following discoveries has not actually been made yet?

(a) channels cut into the surface of Mars which appear to have been carved by water (b) the presence of water frozen into the soil on Mars
(c) the presence of ice caps on Mars
(d) deposits of ice found in the bottoms of deep craters
(e) underground streams on Mars

Answer 1

Evidence for (e) underground streams on Mars has not been discovered yet, unlike other indicators of water such as channels, frozen soil, ice caps, and deep crater ice deposits.

Step-by-step explanation:

The piece of evidence suggesting the presence of water on Mars that has not been discovered yet is (e) underground streams on Mars. While we have seen multiple indications of ancient and current water ice on the planet, such as channels carved by water, water frozen into the soil, ice caps, and ice deposits in deep craters, there is currently no confirmation of flowing underground streams.

The presence of ice on Mars, especially recurring slope lineae suggesting salty liquid water and mudstones that indicate past aqueous environments, has been well documented by missions like the Mars rovers and orbiters.