Though sucking zinc lozenges has been promoted as treatment for the

Question

Though sucking zinc lozenges has been promoted as treatment for the common cold, research has revealed no consistent effect. Recently, however, a zinc gel applied nasally has been shown to greatly reduce the duration of colds. Since the gel contains zinc in the same form and concentration as the lozenges, the greater the effectiveness of the gel must be due to the fact that cold virus tend to concentrate in the nose, not the mouth.

Which of the following, if true, most seriously weakens the argument?

(A) Experimental subjects who used the zinc gel not only had colds of shorter duration but also had less severe symptoms than did those who used a gel that did not contain zinc.

(B) The mechanism by which zinc effects the viruses that caused the common cold has not been conclusively established.

(C) To make them palatable, zinc lozenges generally contains other ingredients, such as citric acid, that can interfere with the chemical activity of zinc.

(D) No zinc based remedy can have any effect unless it is taken or applied within 48 hours of the onset of cold symptoms.

(E) Drug company researchers experimenting with nasal spray based on zinc have found that it has much the same effect on colds as the gel does.

Similar question with the same stem: though-sucking-zinc-lozenges-has-been-promoted-as-a-treatment-for-the-72764.html

Show Spoiler

ID:500401

04735

Show Answer

Official Answer

Official Answer and Stats are available only to registered users. Register/Login.

If this question felt shaky, try an adaptive mini quiz of similar problems in GMAT Club Forum Quiz →. Free plan gives 5 questions per day.

ChrisBKnewton · Accepted Answer

Hi all, here's an answer to this tricky question from one of our CR experts at Knewton, Jonathan Bethune. I hope it's helpful!

This is a very interesting question. The difficulty stems from the fact that the correct answer does not appear to have any direct bearing on the argument.

Start by eliminating the obviously wrong answer choices. Choice A adds details that do not undermine anything in the argument. Choice B is too weak – we don’t really need to know the mechanism by which zinc effects viruses in order to know that it helps beat the cold. Choice D is a random detail. Choice E strengthens the argument because it shows that other zinc-based nasal treatments work just as well as the gel.

Even if you rule out all of the other answer choices, how can we deduce that C is correct? The key here is to keep in mind what the specific argument is: Zinc gel works better than zinc lozenges because cold virus concentrate in the nose. A condition of this argument is the fact that lozenges and gel contain the same concentration of zinc. If the gel had more zinc than the lozenge, then the higher concentration of zinc might account for its increased efficacy.

This is basically what choice C does. It undermines the assumption that both medications contain the same concentration of zinc. If the citric acid in the lozenge is interfering with the zinc, then it is possible that the gel works better simply because its zinc is NOT being interfered with. A lozenge with no citric acid (which presumably would taste awful) might work just as well as the gel. Therefore we cannot assume that the gel works better because cold virus is in the nose. It may be the lack of citric acid that makes the gel work better.

Therefore C is correct.

ykaiim · Answer

IMO C.

Premise 1: Sucking the zinc lozenges has been proved useful treatment but research refutes this claim.

Premise 2: Since the gel contains zinc in the same form and concentration as the lozenges.

Conclusion: Cold virus is in nose, not in mouth.

We have to find that it is not because of virus in nose rather some other factor which is making zinc lozenges less effective for showing consistant effects. Only C survives the test.

ykaiim · Answer

A. Expiremental subjects who used the zinc gel not only had colds of shorter duration but also had less sever symptoms than did those who used a gel that did not contain zinc.  Out of scope  choice.  Incorrect ]

E. Drug company researchers experimenting with nasal spray beased on zinc have found that it has much the same effect on colds as the gel does.  Out of scope  choice.  Incorrect ]

nilesh376 · Answer

wats the question source? I too picked 'A'. Argument contradict lozenges effectiveness to nasal zinc gel which reduces duration of cold, its effectiveness is due to virus concentrated in nose.
zinc gel effectiveness could be weaken by subject experiment already had cold of shorter duration, hence the gel has no effect evn applied to nose.

Not sure how 'C' weakens this zinc gel's effectiveness, it hurts lozenges effectiveness. does anyone have a strong reason??

seekmba · Answer

can someone provide a detailed explanation on how (C) is correct and (A) is incorrect.

sasen · Answer

A is incorrect because IT DOENSOT weaken the arg
C simply provides an alternate explanation for the occurence

meshtrap · Answer

Hi seekmba,

A. Expiremental subjects who used the zinc gel not only had colds of shorter duration but also had less sever symptoms than did those who used a gel that did not contain zinc. [We don't have info on other type of gel. We need to compare the results of zinc based gel and lozenges. Out of scope choice. Incorrect]

E. Drug company researchers experimenting with nasal spray beased on zinc have found that it has much the same effect on colds as the gel does. [We don't have info on other type of nasal sprays. This option is just to mislead us. Out of scope choice. Incorrect]

C. to make them palatable, zinc lozenges generally contains other ingredients, such as citric acid,, that can interfer with the chemical activity of zinc - here, it clearly specifies the ineffectiveness of zinc in the lozenges against the zinc in the and thus weakens the conclusion

Hope that helps,
meshtrap

mmphf · Answer

The argument is not that zinc is effective or that one is more effective than the other. The argument is that the gel is more effective than the lozenges  because  the cold virus is more in the nose than the mouth.

"the greater the effectiveness of the gel must be due to the fact that cold virus tend to concentrate in the nose, not the mouth."

C is the best answer because it gives a different possible reason why the gel is more effective. It's because they add stuff that interfers the the chemical activity of the zinc.

I don't understand how "A" could be correct.

spyguy · Answer

Very difficult to understand exactly why c is correct.

M23A · Answer

Conclusion
Cause: cold virus tend to concentrate in the nose

Effect: gel is more effective

Answer choice (C) weaken this conclusion by suggesting an alternate cause: logzenges is less effective against cold virus

Posted from my mobile device

hermit84 · Answer

IMO C is correct.

The conclusion that effectiveness of gel is because it is directly applied at nose, is weakend by the statement, that in "zinc lozenges" there are some substances along with zinc which can reduce the affect zinc would have.

maddy2u · Answer

IMO C !

C is my choice because it gives another reason to show why Zinc losenges is ineffective.

A strengthens the argument by showing that zinc gel was effective.
E strengthens the conclusion by showing that nasal treatment is superior to ingestion through mouth.

Hope this clarified your doubt. Feel free to PM me if not understood.

reatsaint · Answer

Argument here is old virus tend to concentrate in the nose, not the mouth.

A does not work because, here we are not comparing nasal vs mouth zinc. Here it is basically between gel with zinc and non zinc.

E does not work because, here again comparison between gel and spray, not between nose and mouth gels.

OptimusPrepJanielle · Answer

Though sucking zinc lozenges has been promoted as treatment for the common cold, research has revealed no consistent effect. Recently,however, a zinc gel applied nasally has been shown
to greatly reduce the duration of colds. Since the gel contains zinc in the same form and concentration as the lozenges, the greater the effectiveness of the gel must be due to the fact that cold virus tend to concentrate in the nose, not the mouth.

Which of the following, if true , most seriously weakens the argument?

The argument is that zinc works better in the nose than in the mouth because the cold virus concentrates in the nose. The statement that weakens the argument will provide a different explanation for the efficacy of zinc in the nose compared to the mouth.

A. Experimental subjects who used the zinc gel not only had colds of shorter duration but also had less sever symptoms than did those who used a gel that did not contain zinc. out of scope - We are not interested in comparing zinc and no zinc, nor the specific effects of zinc. 
B. The mechanism by which zinc effects the viruses that caused the common cold has not been conclusively established.  The mechanism of zinc is out of scope. 
 C. to make them palatable, zinc lozenges generally contains other ingredients, such as citric acid, that can interfere with the chemical activity of zinc.   This provides an alternative explanation for zinc's increased efficacy in the nose compared to the mouth. In the mouth zinc's efficacy is reduced by chemical activity with citric acid. 
D. no Zinc based remedy can have any effect unless it is taken or applied within 48 hrs of the onset of cold symptoms.  The time frame in which zinc-based remedies are applied is out of scope. 
E. Drug company researchers experimenting with nasal spray based on zinc have found that it has much the same effect on colds as the gel does.  There's no mention here of oral zinc remedies. This is only comparing two ways to apply zinc to the nose.

AndyDufresne · Answer

Consider a situation where one can either chew Vicks lozenges which treats the cold in say 5 days, versus applying the Vicks gel directly on nose which treats the cold in 1 day. Now if everything being equal, this is what strengthens the argument which states how gel works better because it is directly applied on the area where virus colony is vis-a-vis lozenges which have to work harder for the zinc, the slayer of virus, to be transported through a complex mechanism from mouth to nose.

However, there is a catch. The special additive in the lozenges reduces the efficacy of zinc in it. Hence, it takes 5 days and not 1 day when compared to gel. This additive merely improves taste but as a side effect, reduces efficacy of zinc in it. Which means if we add this same additive to gel, the gel will also take 5 days to treat cold.

Thus, the real difference lies in the presence or absence of an additive and NOT in different areas of application of zinc based medicines.

napolean92728 · Answer

Correct Answer: C  
The argument claims that the zinc gel is more effective than the lozenges because cold viruses concentrate in the nose rather than in the mouth. However, if there is another explanation for why the lozenges are less effective, then the conclusion is weakened.

Option C  states that zinc lozenges contain other ingredients (like citric acid) that interfere with the chemical activity of zinc. This suggests that the lozenges may be ineffective not because of where they are applied (mouth vs. nose), but because their ingredients reduce zinc’s effectiveness.

Thus, the argument's reasoning is weakened—the greater effectiveness of the nasal gel might not be due to the location of the virus but rather due to differences in formulation.

Why the Other Options Are Incorrect:
 A. Experimental subjects who used the zinc gel not only had colds of shorter duration but also had less severe symptoms than did those who used a gel that did not contain zinc. 
This compares zinc gel vs. non-zinc gel, rather than zinc gel vs. zinc lozenges.
It shows that zinc gel is effective, but it does not weaken the argument that its effectiveness is due to where it is applied.
Eliminated because it does not compare lozenges and gel, which is necessary to weaken the argument.
 B. The mechanism by which zinc affects the viruses that cause the common cold has not been conclusively established. 
The argument does not rely on knowing the exact mechanism of zinc's action, only on where the virus is concentrated.
Even if the mechanism is unclear, the nasal gel still showed better results, so this does not weaken the argument.
Eliminated because the argument does not depend on understanding zinc’s mechanism.
 D. No zinc-based remedy can have any effect unless it is taken or applied within 48 hours of the onset of cold symptoms.
 This just states that timing matters for zinc treatments, but it applies to both the lozenges and the gel.
It does not explain why the lozenges were less effective than the gel, which is the argument’s main point.
Eliminated because it does not create a distinction between the effectiveness of lozenges and gel.
 E. Drug company researchers experimenting with a nasal spray based on zinc have found that it has much the same effect on colds as the gel does. 
This just confirms that another nasal form of zinc is effective, which does not weaken the argument that nasal application is the key factor.
It does not challenge the claim that the lozenges are less effective because they are taken orally.
Eliminated because it does not address why lozenges are less effective.

egmat · Answer

This zinc lozenge question tests a common GMAT pattern - identifying alternative explanations. Let me walk you through the core reasoning that will help you solve this one.

Understanding the Argument Structure:

The author observes two facts:
- Zinc lozenges (in mouth) → No consistent effect on colds
- Zinc gel (in nose) → Greatly reduces cold duration

Then makes this conclusion: Since both have  identical zinc form and concentration , the gel must work better  because cold viruses concentrate in the nose, not the mouth .

The Hidden Assumption:

Here's what you need to see - the author assumes that if two treatments have the same zinc form and concentration, they must deliver zinc equally effectively. But what if that's not true?

Evaluating the Answer Choices:

Let's think about what would weaken this location-based explanation...

(A)  The gel reducing symptom severity actually  strengthens  the argument by showing the gel is more effective overall.

(B)  Not knowing the exact mechanism doesn't weaken the location-based explanation - we can still observe where something works better even without knowing exactly how.

(C)   This is our answer!  Notice how this provides an  alternative explanation : The lozenges contain citric acid that interferes with zinc activity. So even though both have the same zinc concentration, the lozenges' zinc is less active due to interference. The difference might not be about virus location at all - it could be about zinc actually working in one form but being blocked in the other!

(D)  This applies to both treatments equally, so it doesn't explain why one works better than the other.

(E)  A nasal spray working like the gel actually supports the nose-location theory rather than weakening it.

The Key Insight:

When an argument says "X must be the reason because everything else is equal," look for answer choices that show everything else  isn't  actually equal. Choice (C) does exactly that - it shows the zinc isn't equally active in both treatments.

---

You can check out the  step-by-step solution on Neuron by e-GMAT  to master the systematic framework for evaluate questions. This solution reveals alternative explanations you might not have considered and shows you how to quickly identify assumptions in similar arguments. You can also explore other GMAT official questions with detailed solutions on Neuron for structured practice  here .

Though sucking zinc lozenges has been promoted as treatment for the

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

GMAT Critical Reasoning (CR) Questions

Though sucking zinc lozenges has been promoted as treatment for the

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia