Sentence Correction (SC) | Re: The Mars Exploration Program

i also chose B. Well the reason is "X, as well as Y, and Z" in this X is the main focus and Y is after thought
X :- to help determine whether Mars could ever have supported life
Y :- to determine the role of water
Z :- to study the climate and geology of Mars

X and Z makes the list so they have to be parallel
Plus in all other options A,C,D,E "determining the role of water" is acting a modifier. So i choose B

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