Geographer: "Sorted circles" are patterned geological formations

Question

Geographer: "Sorted circles" are patterned geological formations consisting of a circular border of stones around a center of finer material. They are found mainly in or near the Arctic and Antarctic. In attempts to explain how they were formed, two hypotheses are currently most commonly debated: one proposes frost, the other heat. But frost cannot be the complete explanation for the uniformity in size of the circles on Marion Island, located in the maritime Subantarctic. Therefore, heat, either in water or in saturated soil, was likely involved in the formation of the circles.

Which of the following would, if true, most weaken the geographer's argument?

A. Field experiments show there is currently frost at all sorted-circle sites on Marion Island.
B. The two hypotheses do not exhaust the possibilities regarding formation processes for sorted circles.
C. The definition given for sorted circles excludes many land features that may be caused by frost or heat.
D. The sorted circles on Marion Island were probably not all formed at the same time.
E. Neither of the two hypotheses explains how stones and finer material came to be on Marion Island in the first place.

MartyTargetTestPrep · Accepted Answer

The author concludes the following:

heat, either in water or in saturated soil, was likely involved in the formation of the circles.

That conclusion is based on these premises:

In attempts to explain how they were formed, two hypotheses are currently most commonly debated: one proposes frost, the other heat.

frost cannot be the complete explanation for the uniformity in size of the circles on Marion Island, located in the maritime Subantarctic.

One aspect of the argument that we may notice is that it says basically the following. Since one thing, "frost," cannot explain the uniformity in size of the circles, another thing, "heat," was likely involved.

So, the conclusion that heat was likely involved is based only the fact that frost alone could not have produced the circles. The argument does not include any direct evidence that heat was involved.

The correct answer will weaken the support for the conclusion or cast doubt on the conclusion.

A. Field experiments show there is currently frost at all sorted-circle sites on Marion Island.

This choice may seem to weaken the argument, but it actually makes no difference. The support for the conclusion, "frost cannot be the complete explanation for the uniformity," acknowledges that frost may exist where the circles are but still cannot explain how they were formed.

So, what this choice says is in line with the argument.

B. The two hypotheses do not exhaust the possibilities regarding formation processes for sorted circles.

As discussed above, the conclusion that heat was likely involved in the formation of the circles is not directly supported. Rather, it's only indirectly supported by the fact that frost cannot completely explain the uniformity in size of the circles.

So, the author is basing the conclusion that heat was likely involved on the fact that SOMETHING other than frost must have been involved.

Thus, if what this choice says is true, then we have less reason to believe that heat was likely involved because there are possibilities other than heat and frost.

What if there are three other possibilities? Then, maybe there's only a 25 percent chance that heat was involved. In that case, the conclusion that heat was "likely" involved no longer makes sense.

So, this choice weakens the support the premises provide for the conclusion.

C. The definition given for sorted circles excludes many land features that may be caused by frost or heat.

This choice has no effect on the argument. It basically tells us that there are things other than sorted circles that may be formed by heat or frost. That information tells us nothing about whether heat was involved in the formation of sorted circles.

D. The sorted circles on Marion Island were probably not all formed at the same time.

We have no reason to believe that  when  the circles were formed is related to  how  they were formed. So, this choice has no effect on the argument.

E. Neither of the two hypotheses explains how stones and finer material came to be on Marion Island in the first place.

The argument is not about how the material came to be on Marion Island. It's about how the circles were formed. So, this choice has no effect on the argument.

The correct answer is  B

pranj123456 · Answer

Please explain the OA. I thought D is the answer

Ritik25 · Answer

This is a purely logical question. While you may be tempted to think of this in terms of geographical reasoning, the actual logic used is much simpler. The argument says that heat "must" have been involved since frost cannot be the "complete" explanation. Option B says that heat and frost are not the only explanations for this phenomenon. Thus the argument's logic that heat "must" have been involved is clearly nullified, if there are options other than frost and heat that can cause the sorted circles.

Oppenheimer1945 · Answer

I accept it that B is correct. But tell me how you can blatantly deny A? What part of the option A triggers that A is wrong and B is right

thelastskybender · Answer

Hello sir!

I understand that B is the correct answer but I was having a hard time eliminating option E. Isn't the question "how the material came to be on Marion Island" a subset of "how the circles were formed" ?

Shivam_Parashar · Answer

I have chosen B because the author thinks that since Frost is not the reason it must be the other (Heat). Now there are two ways to weaken this thaught.
(1) if we can somehow prove that the author's logic behind nullifying Frost is wrong but in this question, he is quoting a study so we can not nullify it and also no option is like that. 
(2)Author is thinking like either - or. if we somehow introduce more factors that could be the reason if not frost then we can easily weaken his conclusion.

MartyMurray · Answer

The conclusion is that "heat ... was likely involved in the formation of the circles."

The support for that conclusion is that there are two proposed causes of the circles, frost and heat, and that "frost cannot be the complete explanation for the uniformity in size of the circles."

So, basically the author is saying that, since frost can't be the complete explanation, in other words, the sole cause, of how the circles are, heat must have been involved.

Now, regarding (A), all (A) says, basically, is that there is some frost where the circles are.

OK, great, but the author has already stated as fact that "frost cannot be the complete explanation for the uniformity in size of the circles." So, regardless of the fact that there is frost there, FROST CANNOT BE THE SOLE CAUSE of the formation of the circles. It may have been a factor. The author never says that frost plays no role in the formation of the circles.

The author's conclusion is simply that "head was likely involved," and the fact that some frost is around doesn't mean that head was not involved.

So, we can eliminate (A).

MartyMurray · Answer

Notice that all the author is saying is, basically, that the shape of the circles indicates that heat was involved in their formation.

That conclusion would be true regardless of what (E) brings up, "how stones and finer material came to be on Marion Island in the first place."

Think about it.

What if waves transported the material to Marion Island? Heat could have been involved in the formation of the circles.

What if birds dropped the material on Marion Island? Heat could have been involved in the formation of the the circles.

The key is to be clear about exactly what the conclusion is so that we don't start broadening it and thinking that things that don't matter matter. In this case, the conclusion is rather specific and simple. It's about heat being involved. Where the material came from has no bearing on that specific conclusion.

vedha0 · Answer

C,D,E are easy eliminations. A is a good trap option. until u see B which hits right at the target.

Raman109 · Answer

Understanding the argument 
Geographer: "Sorted circles" are patterned geological formations consisting of a circular border of stones around a center of finer material. - Fact 
They are found mainly in or near the Arctic and Antarctic. - Fact 
In attempts to explain how they were formed, two hypotheses are currently most commonly debated: one proposes frost, the other heat. - Fact 
But frost cannot be the complete explanation for the uniformity in size of the circles on Marion Island, located in the maritime Subantarctic. - Claim
Therefore, heat, either in water or in saturated soil, was likely involved in the formation of the circles. - Conclusion.

The argument logic is A, and B is the two commonly debated hypotheses. A can't be the complete explanation so B is the likely reason.

Why B is the reason because A is not. But what if there are 5 other reasons? That'll weaken.

Option Elimination -

A. Field experiments show there is currently frost at all sorted-circle sites on Marion Island. - The presence of frost is, in a way, already acknowledged in the argument, but at the same time, the author also shares that it can't be the complete explanation. Distortion.

B. The two hypotheses do not exhaust the possibilities regarding formation processes for sorted circles. - If there are other reasons, then the conclusion that "B is likely the reason" is weakened.

C. The definition given for sorted circles excludes many land features that may be caused by frost or heat. - "Many land features that may be caused by frost or heat" are out of scope.

D. The sorted circles on Marion Island were probably not all formed at the same time. - The time of their formation is out of scope.

E. Neither of the two hypotheses explains how stones and finer material came to be on Marion Island in the first place. - How the material came there is out of scope.

GmatKnightTutor · Answer

Therefore, heat, either in water or in saturated soil, was likely involved in the formation of the circles.

Which of the following would, if true, most weaken the geographer's argument?

B. The two hypotheses do not exhaust the possibilities regarding formation processes for sorted circles.

If someone tells you it's likely that X did something because Y couldn't, that kind of argument would be weakened if someone else mentions that Z could have potentially done it, too. Similarly, answer choice B mentions that there could have been multiple other possibilities.

rmahe11 · Answer

GMATNinja  , I came down to two options that is B and E , I selected B and found to be convincing but when we see D isn't it also saying that apart from heat and frost it can be something else ? like an alternative basically

Diwen2000 · Answer

Hey, I chose B at first glance but chose D at last. 
Doesn't the question already said  two hypotheses are currently  most  debated . It could be that other hypotheses are of small possibilities and are thus not considered. Therefore, B does not weakenes the arguement too much as the geographer has already considered and defended it in advance.
Instead, D could weaken due to some geographic reasons...
Hope for an explanation : )

GMATNinja · Answer

We have no idea how choice (D) would affect the argument: maybe it weakens, maybe it strengthens, and maybe it doesn't nothing at all. There's nothing in the argument about the TIMING of the circle formation, and without further information, we can't conclude that (D) is a weakener.

(E) is out because the argument isn't concerned with the origin of the material. All that matters is how the circles were formed, regardless of where the material came from.

Being the "most commonly debated" hypotheses certainly isn't evidence that those are the BEST hypotheses. The author's argument does not contain any evidence against the existence of a better hypothesis that is not commonly debated at present.

(B) attacks this hole in the argument, so it's the best answer.

I hope that helps!

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Geographer: "Sorted circles" are patterned geological formations

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Geographer: "Sorted circles" are patterned geological formations

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