NASA’s methodical approach to the exploration of Mars has not yet answ

Notice that you used the correct phrasing in your post:



It's "whether those traces CAN exist" and "whether water CAN exist," not "whether can those traces exist" and "whether can water exist". The last two phrases make sense in a question ("Can water exist?") but not in the "whether" constructions seen in this question.

Also, the use of "can" isn't ideal:

• We're interested in these two distinct options: (1) the traces still exist or (2) the traces do not still exist. The "whether" construction in (C) expresses those two distinct options perfectly.
• In (B), the "whether" construction, at best, expresses these two options: (1) the traces CAN still exist or (2) the traces CANNOT still exist. If they CAN exist, does that mean that they DO exist? Knowing that there's a POSSIBILITY that the traces could exist doesn't really get to the simple core of the question: do they still exist, or not?

That's not a DEFINITE error, but the "can" definitely isn't ideal. Also, the use of "if" suggests some sort of conditional statement -- as if the traces can only still exist if we presume that they do? That doesn't make sense.

The "presuming..." part in (C) can logically qualify the question of whether those traces still exist, just as the "assuming..." part can logically modify the question here:

Assuming Bunuel is a real human being, what does he or she eat for breakfast?

The function of the "presuming..." part is clear enough in (C), regardless of what EXACTLY in modifies. Even if we chalk that up as a small vote against (C), (B) has more significant issues -- issues that affect the meaning.

I hope that helps!
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Dear experts GMATNinja DmitryFarber IanStewart AndrewN AjiteshArun zhanbo RonTargetTestPrep

I've checked all posts in the thread but I still would like to discuss (A) further.
My final two candidates were (A) and (C), but as I thought that each has pros and cons, I could not decide.

NASA’s methodical approach to the exploration of Mars has not yet answered the questions of whether biological life forms ever emerged on Mars and whether, presuming such life forms having left fossil traces to begin with, those traces can still exist in some moist recesses of the cold and arid planet.

(A) and whether, presuming such life forms having left fossil traces to begin with, those traces can
(C) and whether, presuming such life forms left fossil traces to begin with, those traces

1. "presuming"

Because there was no maker "that" in neither options, I actually preferred (A) to (C). I knew the part beginning with "presuming" in both options is not structured in the "comma+ing" form, but I did not know whether "presuming" is a preposition or conjunction. I thought that maybe it is better for "presuming" to precede a noun, like "such life forms having left..." rather than a clause, like "such life forms left...."

Yes, I agree that (A) is uglier, and I am aware that the lack of "that" is quite common in the real world. But...GMAT world is so strict so I was concerned. At least, is not (A) better than (C) in grammatical sense?

Secondly, as a non-native speaker, I heavily rely on dictionaries to learn how to use words, but such use of "presuming" in (C) is not explained by dictionaries, such as Cambridge or Webster. (On the other hand, "assuming (that)" mentioned by GMAT Ninja is clearly explained by dictionaries saying "assuming" serves as a conjunction.) Yet, since (C) is the right option, I will accept it and pick it up. (Maybe it serves as a conjunction too.)

2. "Having left" in (A)

GMAT Ninja has explained in his previous post why he thinks "having left" does not make sense, but I hope to discuss this tense more. Perfect tense is often used to refer to an action that has been completed in the past but still has an impact on the present, so I think that the use of prefect tense is actually not that bad in (A): if the life forms have left some traces on Mars, NASA wants to know whether the traces still exist in the planet, even though NASA has not got the answer.

Yes, I agree that the Ving form "having left" is weird, but I did not think that it is a definite error. Rather, I thought that it is just a necessary "change in form" since we want to use a noun "such life forms having left..." to follow "presuming."

I am not against the use of simple past tense in (C). It is just that I cannot see why "having left" in (A) is wrong.

Thanks in advance for your sharing!

Dear Friends,

Here is a detailed explanation to this question-

Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended meaning of the crucial part of this sentence is that NASA’s methodical approach to the exploration of Mars has not yet answered whether fossil traces left by biological lifeforms on Mars still exist in some moist recesses of the cold and arid planet.

Concepts tested here: Meaning + Verb Forms + Pronouns + Idioms + Awkwardness/Redundancy

• Actions that concluded in the past are conveyed through the simple past tense.
• “if” is used to refer to phrases that lead to a “then” clause, and “whether" is used for showing alternatives; "whether" generally wins over "if" on GMAT.

A:
1/ This answer choice alters the meaning of the sentence through the phrase "can still exist"; the use of "can" incorrectly implies that NASA’s methodical approach to the exploration of Mars has not yet answered whether it is possible for fossil traces left by biological lifeforms on Mars to still exist in some moist recesses of the cold and arid planet; the intended meaning is that NASA’s methodical approach to the exploration of Mars has not yet answered whether fossil traces left by biological lifeforms on Mars practically still exist in some moist recesses of the cold and arid planet.
2/ Option A incorrectly uses the present participle ("verb+ing") phrase "having left" to refer to an action that concluded in the past; remember, actions that concluded in the past are conveyed through the simple past tense.

B:
1/ This answer choice alters the meaning of the sentence through the phrase "whether...can those traces"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that NASA’s methodical approach to the exploration of Mars has not yet answered whether fossil traces left by biological lifeforms on Mars still exist in some moist recesses of the cold and arid planet.
2/ Option B uses the needlessly wordy phrase "if it is presumed that", leading to awkwardness and redundancy.

C: Correct.
1/ This answer choice uses the phrase "whether...those traces still exist", conveying the intended meaning - that NASA’s methodical approach to the exploration of Mars has not yet answered whether fossil traces left by biological lifeforms on Mars practically still exist in some moist recesses of the cold and arid planet.
2/ Option C correctly uses the simple past tense verb "left" to refer to an action that concluded in the past.
3/ Option C correctly uses "whether" to show alternatives.
4/ Option C avoids the pronoun ambiguity seen in Options D and E, as it uses no pronouns.
5/ Option C is free of any awkwardness or redundancy.

D:
1/ This answer choice alters the meaning of the sentence through the phrase "can still exist"; the use of "can" incorrectly implies that NASA’s methodical approach to the exploration of Mars has not yet answered whether it is possible for fossil traces left by biological lifeforms on Mars to still exist in some moist recesses of the cold and arid planet; the intended meaning is that NASA’s methodical approach to the exploration of Mars has not yet answered whether fossil traces left by biological lifeforms on Mars practically still exist in some moist recesses of the cold and arid planet.
2/ Option D incorrectly uses "if" to show alternatives; remember, “if” is used to refer to phrases that lead to a “then” clause, and “whether" is used for showing alternatives; "whether" generally wins over "if" on GMAT.
3/ Option D suffers from pronoun ambiguity, as it is unclear whether "they" refers to "biological life forms" or "fossil traces".
4/ Option D uses the needlessly wordy phrase "did leave", leading to awkwardness and redundancy.

E:
1/ This answer choice incorrectly uses "if" to show alternatives; remember, “if” is used to refer to phrases that lead to a “then” clause, and “whether" is used for showing alternatives; "whether" generally wins over "if" on GMAT.
2/ Option E suffers from pronoun ambiguity, as it is unclear whether "they" refers to "biological life forms" or "fossil traces".
3/ Option E uses the needlessly wordy phrase "to have left", leading to awkwardness and redundancy.

Hence, C is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~2 minutes):



To understand the concept of "If" versus "Whether" on GMAT, you may want to watch the following video (~1 minute):



All the best!
Experts' Global Team
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