People who are allergic to cats are actually allergic to certain prote

Fact 1: People are allergic to certain proteins found in cats' skin secretions and saliva (not the cat itself)
Fact 2: Each allergy sufferer is allergic to different proteins.

Premise 1: All cats shed skin and spread saliva around their environment
Premise 2: A given cat could cause allergic reaction in some people

Conclusion: All cats are capable of provoking allergic reactions.

(A) This choice is logically wrong.

"X is linked to some of Y" doesn't mean that "Y is linked to some of X". There could be a certain member of Y is linked to all of X or none of X.

(B) This choice is too extreme. There could be a member of X is linked to all of Y.

(C) Not all cats are identical with respect to the proteins contained in their skin secretions and saliva.
Correct. This choice means that some cats have identical proteins contained in their skin secretions and saliva and some cats have different proteins contained in their skin secretions and saliva.

(D) Comparison between allergic reactions is out of scope.

(E) The argument doesn't mention anything about predicting whether a given cat will produce an allergic reaction in a particular allergy sufferer.

A tough question.

The stimulus provides some information:
(1) People are allergic to proteins in the skin of cats. Different people are allergic to different proteins.
(2) Cats shed skin and saliva around their environment.
(3) A common cat can cause an allergic to some, not all, people who are allergic to cats.

It is hard to predict the answer for Inference question. Then using the elimination approach is recommended.
(A) says that ALL people are allergic to cats. This is not correct. Info (3) limits the scope of the argument to "people who are allergic to cats". --> WRONG
(B) From (1), we know that if a cat has all proteins that can trigger allergies, the cat can cause allergy to all types of allergy sufferers.--> WRONG
(C) From (3), we know that a COMMON cat can cause an allergy to some allergy sufferers but not others, who are allergic to other cats. This fact suggests that not ALL cats share the same proteins. --> CORRECT
(D) We do not have any information about intensity of allergy.--> WRONG
(E) We do not have any information about whether it is possible to predict or not.--> WRONG

VeritasKarishma GMATNinja can you provide an insight on this question? can't figure out why c is right.

LSAT Logical Reasoning questions can be a good way to practice GMAT™ Critical Reasoning questions, although the nuances of the former may prove more difficult. In this case, the question stem asks us to make a logical conclusion based on the information provided, similar to a fill-in-the-blank question on the GMAT™. I offer my take on each response below in an effort to assist the community.

The passage lays out a breadcrumb trail of information for us to follow. The question is, which crumb do we need to pick up? What can we disprove?


Analysis: This answer choice represents a clear overstatement: any particular individual will be allergic. Notice that the passage starts with a subset of people, those who are allergic to cats specifically. We cannot assume that all people must be allergic to some cats. Red light.


Analysis: This is a tricky response, but look carefully at what the passage states concerning the issue: it is common for a given cat to cause an allergic reaction in some - but not all - people who are allergic to cats. What about uncommon cases? Furthermore, the answer choice refers again to a larger group of people that the passage is unconcerned with, all types of allergy sufferers. We are only interested in people who are allergic to cats. Watch out for overreaching language (here, all). Red light.


Analysis: This is nearly verbatim what the passage states in the first sentence. We understand that people who are allergic to cats are in fact allergic to certain proteins found in the animals' skin secretions and saliva. It is the next part of the sentence, though, that seals the deal, since we come to understand that the particular proteins responsible for causing the allergic reaction in a sufferer will vary from one person to another. You might interpret the part after the semicolon as saying that the response of the sufferers to the same proteins varies, but the grammatical structure of the which clause calls for the former read. Look at it again, minus the transition: which particular proteins are responsible varies. The proteins themselves are varying or not identical. Green light.


Analysis: Here we go again, focusing on a comparison to other allergy sufferers. Such a concern goes beyond the scope of the passage, which, again, focuses exclusively on people who are allergic to cats. Just check the first and last few words of the passage if you are unsure. Red light.


Analysis: This is another good trap answer. The thinking might go that if a given cat might produce a certain concoction of proteins, perhaps a particular allergy sufferer will or will not be affected by that particular concoction of proteins. But the definitive language in no way ought to warrant caution--if only three protein secretions were possible and only a handful of cat-allergy sufferers existed, then you could make predictions--not to mention that, look again, a particular allergy sufferer could refer to any allergy sufferer, and we have covered this out-of-bounds group already in choices (A), (B), and (D). In sum, every answer choice except for the correct one asks us to draw in a group of people of which the passage makes no mention. Put this answer into the same bin with the rest. Red light.

I hope that helps anyone who stumbles upon this question. As always, I want to wish everyone good luck with their studies.

- Andrew

I have a major problem with this question.
Like other fellow GMAT practitioners, I narrowed down to B and C.
I’m not quite convinced by all the explanations given by the great experts above. I say that with utmost respect to them, by the way. I just wanted to humbly provide my contrarian view and to record my thought process so that one day when I look back with the fresh mind, I can perhaps see where I went wrong.

(B) No cat is capable of causing an allergic reaction in all types of allergy sufferers.
If this choice is not right, it means that:
Some cats are capable of causing an allergic reaction in all types of allergy sufferers? Really? It doesn’t sound right to me because the stem says:
“Which proteins are responsible varies from allergy sufferer to allergy sufferer.”
So doesn’t this sentence loosely mean that ‘one cat cause an allergic reaction in one allergy sufferer but not necessarily in another’?

The only case that I can think of and that one cat is capable of causing an allergic reaction in all types of allergy sufferers is if the cat carries all proteins that potentially cause some allergic reaction in all types of allergy sufferers. If so, then, yes, (B) is wrong, because there are some cats that can cause some allergic reaction in all types of allergy sufferers. So the cat must be some monster cat. I mean, from the commonsensical perspective, this is very unlikely, but as per the stem, that’s something that we have to live with? Well, I feel very uncomfortable with the decision.

Now, let’s dissect C.
Yes, I can see why C is the right answer.
The problem that I have with C is that I can think of a scenario, in which C does not hold up but is still consistent with the stem.

I’m no expert in biology or zoology, but let’s imagine a scenario in which the cat, as a species, commonly carries a set of proteins, such as A, B, C, D, & E, that cause allergic reactions in people.

Some allergy sufferers are allergic to A, but not B.
Some allergy sufferers are allergic to C, but not E, and so on.

Perhaps, all cats, the cat as a species, equally carry an identical set of proteins, but it just so happens that some proteins trigger allergic reactions in some allergy sufferers but not in others. As unlikely as it may sound, is this scenario inconsistent with the stem? No, it is still consistent. So, (C) “not all cats are identical with respect to the proteins contained in their skin secretions and saliva”? Well, most likely, but perhaps all cats carry the same proteins but people react differently.

I had trouble just like you in B and C, and chose B over C for something similar as your reasoning.
However, first, thinking of a scenario after eliminating 4 options is not the right way - its like axing your own foot. Anyway it is a nice way to practice.

People reacting differently is out of question here as i think, since no options deals with such a parameter. Neither it is dealt in the argument itself. If you just ignore the second red text then you have nicely reached to C, as it is only thing that may be possible - read the first sentence prior to semi colon(i didn't pay much attention to it) of passage. Since it is found that people are allergic to certain proteins of animals - here cats - it is possible that not all cats have same proteins. This is in line to first sentence after semi colon.

Hello expert,
I'm confused why C is right. Is there such a possibility as: assuming all cats contain the same protein A, B, C. The passage says “which protein is responsible for the allergy varies from sufferer to sufferer” , so let’s say: some people are allergic with protein A, some people are allergic with protein B, and some people are allergic with protein C (and also some people are not allergic with all ABC proteins——this group of people is not allergic with cats).

And yes I noticed the last sentence says “it is common for a given cat to cause an allergic reaction in some - but not all - people who are allergic to cats”, but this is just a common case, not an abosult case. So if the possibility above exists, then C is not correct.
Hope expert helps and much thanks.

Let us call your assumption X.

X = all cats contain the same protein.
The statement in option C = NOT X = Not all cats are identical with respect to the proteins

Conclusion of the passage, say Y = a given cat will cause an allergic reaction in some, but not all.
So, NOT Y = a given cat will cause an allergic reaction to all.

Your argument is:
If X is true, then you cannot conclude that NOT Y is true.

However the above argument is not dicussed in the question - the question deals with the following argument:
If NOT X true, then you can more strongly conclude that Y is true.

So summarily you are thinking on a different argument (X ---> NOT Y) than that given in the passage (NOT X ---> Y).

Take a look at the exact language of the question:

Here, we're looking for something that is more strongly supported than the other answer choices. That's much different than looking for something that is an "absolute case," as you've mentioned.

You're on track with the key detail in the passage: It is common for a cat to provoke an allergic reaction in some, but not all, people. Additionally, these reactions are caused by different particular proteins found in the cats' skin and saliva.

These facts combined support the information in (C): Not all cats are identical with respect to the proteins contained in their skin secretions and saliva. If all cats WERE identical in this way, then it wouldn't be "common" for only some people to have an allergic reaction to a given cat.

(C) is the correct answer.

I hope that helps!

Hi AndrewN

Though I got the correct answer, my reason for eliminating option B was slightly different. "No cat" was a red light when I first read the statement. It would, however, make sense in practical life as a single cat cannot cause every type allergy there is. But in the question, no specific emphasis on the potency of cats to cause allergy was mentioned. Hence I eliminated it. Was my line of thought correct ?
Correct option C is much more clearer and kind of binds the whole gist of the paragraph. I am just interested in knowing if my thinking was on the right tract to eliminate B.

Hello, Namangupta1997. I am never going to say that my line of reasoning is the only valid one. In fact, I encourage sharing views that may differ from my own. I call matters as I see them, nothing more. You are correct in saying that the passage does not provide enough information for us to be able to comment on whether any single cat can cause the allergic reaction described in answer choice (B). That makes (B) untenable. People get into trouble with these types of questions because they chase unsubstantiated but reasonable-sounding options. (Sometimes I still do this myself.)

Thank you for following up. If you answered the question correctly, well done.

- Andrew

My take:

Although I got the question wrong at first, but a careful reading of the stimulus suggests that:

If all the cats had same protein/s then, all the people who are allergic to different different proteins found in the saliva/secretion will respond but since not all are responding to a given cat, it means that different cats have different proteins.

For example: Lets assume Alex is allergic to protein B found in the cat and Rosa is allergic to protein Q. If they happen to be in a location where there is a cat, Alex responds by sneezing but nothing happens to Rosa. If a cat has all the proteins from A to Q, then Rosa would have had some reaction but she didn't.

This only means that proteins in the cats vary. A single cat might have ABC and the other might have OPQ etc.