Which sentence best supports the key concept that preservation is as important as exploration?
A."NASA's Kepler mission has discovered thousands of potential planets around other stars, indicating that Earth is but one of billions of planets in our galaxy." (Paragraph 2)
B."I study planetary habitability as influenced by stars with the hopes of finding the places in the universe where we might discover life beyond our own planet." (Paragraph 4)
C."Indeed, it's possible that Mars was habitable in the past, and in part, this is why we study Mars so much." (Paragraph 6)
D."If we truly believe in our ability to bend the hostile environments of Mars for human habitation, then we should be able to surmount the far easier task of preserving the habitability of the Earth." (Paragraph 12)
LET'S NOT USE MARS AS A BACKUP PLANET
by Lucianne Walkowicz