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.

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]

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

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. - Here, the stmt compares the zinc gel with another zinc gel and not the zinc lozenges. The first part of the stmt does allure you into selecting this option but the latter part clearly deviates.

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

Very difficult to understand exactly why c is correct.

+1 C
_________________

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.

well explained mashtrap ... kudos for you

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.

Cause and Effect passage.
Argument says, Cause (Application of Zinc in nose not in mouth) has created an effect ( Consistent result, to tackle cold).

typical Weakener for CE passage can be any of the following
1. Alternate cause
2. Effect causing Cause
3. Effect happen before cause.

Lets try to find the above pattern in option choice.
Only Option C, gives me the alternate cause for the effect.

Hence Option c is more appropriate.