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Critical Reasoning Questions are all about distractions. One is supposed to not only trace the logic behind the task but also to see through the author’s sneaky plan of leading the great minds struggling with the GMAT astray. Therefore, cracking a Critical Reasoning question can resemble an attempt to go through King Minos’ labyrinth with the difference being that those scoring well on the GMAT are equipped with USEFUL techniques and strategies instead of Ariadne’s thread.

A typical CR question may have from one to three answer choices going beyond the question’s scope and their elimination can be a matter of seconds. However, having eliminated the obvious we find ourselves with that uncomfortable problem of having to choose between seemingly tasty alternatives. The dilemma is made even more frustrating with the realization that such choices make or break our GMAT scores!

To survive in this hostile environment it is crucial to know your enemy – to understand how distractors work. They are commonly referred to as trap-answer choices and their elimination is never automatic; a good distractor seems plausible in some way. The question structure also renders more than one answer appealing. Consider this question:

Two farmers, who never left their farms their whole lives, were looking at their dogs and observed that all their border collies were black and white. The border collies were the only things that the farmers ever saw as a mix of black and white. Farmer Gil luckily but correctly observed that if something is a border collie then it must be black and white. Farmer Geva then remarked that if something is not black and white, then it is not a border collie.

The argument is flawed primarily because Farmer Geva:
A. fails to realize that there are other dog breeds apart from border collies
B. fails to realize that being black and white is a necessary but insufficient condition to be called a border collie
C. lacks sufficient information on which to base the condition for being a border collie
D. only observes one type of phenomenon – border collies and their color
E. demonstrates only limited knowledge about the world outside

Before approaching this question, we need to determine its type. The question stem tells us that this is an Argument Flaw question; what is the inherent flaw in the argument’s conclusion or its underlying assumption?

In this argument, the first three sentences are the premises, citing facts. Sentence 4 is the conclusion, as it demonstrates an opinion based on the premises:

Premise A: Two farmers, who had never left their farms, saw that their border collies were black and white.
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Premise B: Both farmers had never seen other things that were black and white apart from the dogs.
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Premise C: Farmer Gil: all border collies must be black and white.
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Conclusion: If something is not black and white, it is not a border collie.

Fairly easily, we can eliminate answers A, D and E.

Answer A is incorrect because it assumes too much – that Farmer Geva is unaware of other breeds. Even if this were true, would this make the argument stronger? Is this really the flaw? Not really, as the argument only needs to deal with one dog breed.

Alternatively, choice D criticizes the argument for considering only one phenomenon. However, this is not a flaw as the argument only deals with one type.

Finally, answer E can also be easily rejected. It mirrors what the premises already state – that they had never left their farms and knew no other dog types except border collies; therefore, this answer choice does not illustrate the flaw.

It is clear that the toss-up will be between B and C: both answer choices relate to the scope we defined. Then which is the best answer choice? Which is the correct answer choice and which is the nasty distractor?

At this point we must pause and compare the two answer choices more carefully:

(B) fails to realize that being black and white is a necessary but not a sufficient condition to be called a border collie

(C) lacks sufficient information on which to base the condition for being a border collie

The two statements seem similar, but there are microscopic differences. According to answer B, going on the information of Farmer Gil that all border collies are black and white, Farmer Geva supposes that this is enough for a border collie to be called as such, wrongly assuming that only color delineates what a border collie is, whereas there may be other conditions which make border collies what they are.

Answer C, on the other hand, suggests that Farmer Geva lacks sufficient information to be able to define what a border collie is. Clearly this is not the case – the premises state that Farmer Gil correctly points out that all border collies are black and white and also, as one of the conditions for being a border collie (i.e. being black and white) is a premise, then such factual data is considered correct.

Once we isolate this difference, it becomes easier to judge which answer choice is best: Answer C makes a claim that contradicts the premises, whereas answer B correctly indicates a flaw in Farmer Geva’s reasoning.

The correct answer choice is B.

Take home lesson

Remember that GMAT questions often yield to the scheme of 3 + 1 + 1. Three relatively easy eliminations, a distractor and a correct answer choice. Find the three quickly, and then pause for a microscopic look at the last two. Do your best to choose the best, and not the second best answer choice.