The features of the floor of the Kasei Valles on Mars look just like those at the base of Antarctic ice streams, so it suggests that possibly it was flowing ice that carved the giant Martian channels previously attributed to cataclysmic floods.

(A) so it suggests that possibly it was flowing ice that
(B) a suggestion that flowing ice may have
(C) to suggest flowing ice as possibly having
(D) suggesting that flowing ice may have
(E) which is suggestive of flowing ice having possibly

My doubt w.r.t the OA is , who is doing the act of suggesting ? Along with providing further information/results of the preceding clause, an -ing modifier must also make sense with the subject. Isn't it true ?

A- Wrong pronoun. Pronoun can only refer to noun. But here "it" refers to action.
B- How can the sentence before the comma be " a suggestion". Wrong meaning. But no grammatical mistake.
D- "suggesting" is modifying the action of the previous sentence

Don't 'suggest and possibly' together indicate redundancy in choices A, C, and E and offer an entry into the question?
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The features of the floor of the Kasei Valleys on Mars look just like those at the base of Antarctic ice streams, so it suggests that possibly it was flowing ice that carved the giant Martian channels previously attributed to cataclysmic floods.

Just like [color=#0000ff]noun (features of the floor, in this case)
Just as verb/act (you are getting confused with 'look', in this case)[/color]

I would suggest to please use Aristotle Sentence Grail (and possibly with Manhattan SC guide). Those are the best for non natives.
In fact all the Aristotle books are good for verbal. And then use this forum to solve the questions, difficulty and/or category wise.
Thanks to founders of this forum, who NOT ONLY have build this forum BUT ALSO have contributed in the best possible ways, as members.
https://gmatclub.com/forum/sentence-correction-question-directory-topic-and-difficulty-129750.html
https://gmatclub.com/forum/critical-rea ... 28861.html

[color=#790000]Please Press kudos, if this has helped you.[/color]
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A suggestion (by whom?)...

Makes the voice passive, which is mostly NOT preferred by GMAT.

hope this helps.
Please press KUDOS, if my efforts have helped you gain something.
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