12 Days of Christmas GMAT Competition - Day 1: The 1918 flu pandemic

Manhattan Prep Official Explanation

First Glance: Differences in the answer choices provide clues about what a problem might be testing. Before reading the sentence, glance at the beginning of the underline and down the beginning (just the beginning!) of the five answer choices to look for one early clue as to what this sentence is testing. In this sentence, the beginning of each choice is either due to or because of. These expressions introduce modifiers, so keep an eye out for modifier issues as you read the sentence.

In this sentence, it turns out that the due to vs. because of split in this problem is a red herring; the way in which each one is used in each choice is correct. In addition, even if this difference hadn’t been a red herring, this particular grammar issue can be confusing. When you see an issue that you know is tricky for you, scan the answers for other differences that you find more straightforward to handle.

Issues:

(1) Modifier/Meaning

The modifier at that time moves around in the sentence. Any time you see a time marker moving around in the sentence, check the meaning; placing the time marker in the wrong position can result in illogical meaning. First, what does at that time refer to? It must refer back to a time that was already mentioned earlier in the sentence—in this case, 1918.

Choices (A) and (E) talk about the predominant flu strain at that time. That’s an acceptable meaning—a particular strain of flu predominated in 1918.

Choice (B) talks about molecules … that are necessary for normal immune function at that time. At that time should refer back to 1918, but the quoted text talks about molecules that are (still, currently) necessary for normal immune function. You can’t say that they are (currently) necessary in 1918. Eliminate (B) for illogical meaning.

Choices (C) and (D) say to overproduce certain molecules, called cytokines, at that time. The comma creates an ambiguity. Was it the case that the molecules were only called cytokines at that time…but maybe later the name was changed? (And if that’s the case, why doesn’t the sentence provide the new name?) Or maybe it means that the molecules were only overproduced at that time? It’s not clear. Eliminate (C) and (D) for ambiguous meaning.

(2) Parallelism/Meaning
Answers (A) and (C) use a different structure than answers (B), (D), and (E):
(AC): predominant flu strain provoked healthy immune systems to overproduce certain molecules
(BDE): predominant flu strain provoked healthy immune systems and overproduced certain molecules

What’s the difference between to overproduce and and overproduced? Quite a bit, actually! In the first construction, the flu caused immune systems themselves to do a certain thing. The second construction, however, says that two different things are happening: The flu provoked healthy immune systems and, separately, the flu overproduced certain molecules. There are two problems here. First, the flu provoked the immune systems…to do what? The information isn’t given. Second, the flu didn’t directly produce those molecules! Rather, the flu caused immune systems to overproduce the molecules. Eliminate choices (B), (D) and (E) for illogical meaning.

Note: The GMAT won’t expect you to know how the flu or human immune systems work. The last part of the sentence indicates that cytokines are part of the normal functioning of the immune system—that is, cytokines are present all the time, even when people don’t have the flu. The 1918 flu unfortunately caused people to produce an abnormal number of cytokines rather than a normal number.

The Correct Answer: Answer (A) correctly places the time marker: the predominant strain of flu at that time (in 1918). Further, it conveys the logical meaning that this strain of flu provoked immune systems to overproduce cytokines. This meaning fits with the later information that human immune systems always have/use cytokines but having too many of them can cause problems.
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My attempt.

(A) due to the fact that the predominant flu strain at that time provoked healthy immune systems to overproduce certain molecules, called cytokines, that are necessary for normal immune function

(B) due to the fact that the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function at that time. the flue strain did not overproduced certain molecules, it is the provocation of the immune system

(C) because the predominant flu strain provoked healthy immune systems to overproduce certain molecules, called cytokines, at that time that are necessary for normal immune function. at the time should be modifying flu strain

(D) because the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, at that time that are necessary for normal immune function. same error as in B

(E) because the predominant flu strain at that time provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function. Same error as in B

Ans choices B,C & D are incorrect as the phrase "at that time" is placed incorrectly. Contextually "at that time" refers to the year 1918 which is not made apparent in these incorrect ans choices.
Ans E states the flu did two things, provoked and overproduced. However, the correct ans should be provoked the healthy immune system TO overproduce - hence ans A is correct

We can easily eliminate options B, D and E because they mean that Flu strains are producing Cytokines but in fact it is our own immune system that is producing them. Hence the answer is in between A & C. In C - at the time is awkward. By process of elimination, anwser is A

In my opinion, the main sense-related split here is:

- provoke the immune system and overproduce (B, D, E)

- provoke the immune system to overproduce (A, C)

In my opinion, when the system is just provoked (not to do sth), it doesn't make any sense - so I choose options A and C. And between those, in option С the placement of at that time is really awkward - therefore, the option A is the correct answer.

(A) due to the fact that the predominant flu strain at that time provoked healthy immune systems to overproduce certain molecules, called cytokines, that are necessary for normal immune function
-> seems correct, though I wonder if the sentence isn't trying to refer to the 'predominant flue strain'.

(B) due to the fact that the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function at that time
-> the strain isn't producing the cytokines, the immune system is; at that time presumably makes referene to the date, though this doesn't make sense within the sentence, as cytokines are presumably necessary for normal immune function at all times, not just in 1918.

(C) because the predominant flu strain provoked healthy immune systems to overproduce certain molecules, called cytokines, at that time that are necessary for normal immune function
-> again with at that time

(D) because the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, at that time that are necessary for normal immune function

(E) because the predominant flu strain at that time provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function

The 1918 flu pandemic is thought to have been unusually virulent due to the fact that the predominant flu strain at that time provoked healthy immune systems to overproduce certain molecules, called cytokines, that are necessary for normal immune function but can lead to multisystem organ failure when present in large quantities.


(A) due to the fact that the predominant flu strain at that time provoked healthy immune systems to overproduce certain molecules, called cytokines, that are necessary for normal immune function

(B) due to the fact that the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function at that time

(C) because the predominant flu strain provoked healthy immune systems to overproduce certain molecules, called cytokines, at that time that are necessary for normal immune function

(D) because the predominant flu strain provoked healthy immune systems and overproduced certain molecules, called cytokines, at that time that are necessary for normal immune function

(E) because the predominant flu strain at that time provoked healthy immune systems and overproduced certain molecules, called cytokines, that are necessary for normal immune function

Took me 2:25 to answer this one. I was very confused between A and E and ended up choosing E, though now I feel the answer should be A. So my explanation below is for why A must be correct.

A: due to correctly modifies the fact. The location of "at that time" is correct here as it mentions information about the flu strain in 1918. The main point of distinction among all options is between the usage of "and" and "to". Since the flu strain could not have overproduced the molecules it must have provoked the healthy immune system to do so. Hence, "to" is correct and the meaning seems to be pretty clear here.

B: "and" is used. As mentioned above, "to" must be used.

C: If you remove "called cytokins" between the commas and read the sentence as "......to overproduce certain molecules, at that time that are necessary for normal immune function.....", the placement of "at that time" seems awkward and wrong. Frankly, doesn't make sense to me.

D: Use of "and" and placement of "at that time" seems wrong.

E: Though I chose this as the answer, I now understand that the use of "and" is wrong here. I hadn't fully understood the meaning of the sentence when I had clicked on E. This shows how important meaning is in SC.

Experts, please let me know if my explanation and understanding of the question is correct.

I just want to comment on the "because of" vs "due to part".

I think "due to" is wrong here.

thought (to be x) because (xyz). Because here modifies thought - which is a verb. Hence "due to" is wrong here.

Please correct me just on this part GMATNinja ExpertsGlobal5 egmat VeritasPrepRon EducationAisle

Hello Navaneethcs,

We hope this finds you well.

To answer your query, "because of" and "due to" are both used to refer to the cause of some action and are said to modify that cause; in Option A, "due to" is correct because the cause is expressed through the noun phrase "the fact that...".

Another way to look at it is that "because of" must be followed by a verb or clause and "due to" must be followed by a noun.

We hope this helps.
All the best!
Experts' Global Team
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What does "due to" modify here? Is it modifying "virulent"?

Also in option C, time is singular and after that we have "are", which is plural, so logically it should modify molecules.

The 'due to...' answers 'why?' and hence works as an adverbial.
Normally, 'due to' works as an adjective but the options with 'because' certainly don't work.
Since it is not an official question, I won't worry too much about it.
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