U.S. astronauts will return to the moon in 2024. They will go to Mars in the 2030s. What do we know about Mars?
(Pick the best answer.)
Mars is a more hostile world, because it experienced catastrophic climate-__.
a. changed
b. change
c. crisis
The answer is b, change, because 'climate' is a hyphenated
(It has a hyphen: - ) noun acting as a modifier, an adjective, so the attached, next word--after the hyphen--must be the noun showing what Mars experienced.
C would work, too, but a crisis is experienced by people or other beings and as far as we know, no one lived on Mars when it lost its ocean and magnetosphere! But I guess the clues are in the sands of that frozen desert word! We shall find out when men and women go there in ten years!