The rovers named Spirit and Opportunity that recently explored the surface of Mars discovered:
A) tiny streams of flowing water too small to be detected by orbiting satellites
B) minerals that must have formed in an environment rich in liquid water
C) dust storms that rapidly erode the surfaces of most geological formations
D) the northern polar ice cap is made primarily of frozen water ice
E) the presence of methane that arises from biological life

Question

Quizplus · Accepted Answer

The rovers discovered minerals that could only have formed in a liquid water environment, indicating that Mars had a wetter past.

Answer: E 
 Although early observations suggested the presence of methane on Mars, recent studies have been inconclusive, with some studies indicating the presence of methane and others not. The discovery of methane would be a strong indicator of the presence of biological life on Mars.

The Rovers Named Spirit and Opportunity That Recently Explored the Surface