Ordinary mountain sickness, a common condition among mountain climbers

The best way to proceed when you're down to answer choices (A) and (C) like this is to apply the negation test. This is a necessary assumption question, so the the assumption is needed for the conclusion to be true. Without the assumption the conclusion would be undermined.

So negate the answer choices one-by-one and when you negate the correct answer that should destroy the conclusion. So let's keep track of what the conclusion is. The argument concludes that cerebral edema is especially dangerous at high altitudes.

Negate answer choice (A)
The treatment for ordinary mountain sickness does not differ from the treatment for cerebral edema.

Well if the treatment is the same, then cerebral edema is not especially dangerous at high altitudes because if the climbers treated for ordinary mountain sickness instead of cerebral edema, the climbers would still be treating the cerebral edema - the treatments would be the same.

Negate answer choice (C)
Ordinary mountain sickness involves some disruption of blood circulation in the brain.

Even if this were true, cerebral edema could still be especially dangerous at high altitudes. The answer choice is not about cerebral edema in any way, and so doesn't challenge the conclusion in any way. Thus answer choice (C) is not correct


by manhattan

Imagine you have fever and typhoid. Symptoms of both are same at the beginning - high temperature and weakness. Now if you aren't able to distinguish the two based on these 2 symptoms, then a pill to cure fever will not help you to cure typhoid.
Option A essentially tells that the treatment of one will not work for the other and the person may die because of not getting the apt treatment ---> strengthening the conclusion that cerebral edema is especially dangerous at high altitudes (due to the similarity in symptoms).

the answer should be A,although have a doubt on C too can someone explain a better reasoning to eliminate C?

The answer to this question lies in the last line of the question which states that "Since the symptoms of cerebral edema resemble those of ordinary mountain sickness, cerebral edema is especially dangerous at high altitudes. "

Now since the symptoms of cerebral edema and mountain sickness are similar so how does the author conclude that cerebral edema is dangerous whereas "most people can recover" from mountain sickness. This is because the cure for both are not the same, so if someone develops symptoms of cerebral edema which is similar to mountain sickness so he will treat himself for mountain sickness and not cerebral edema. This makes it dangerous.


Option C states "Unlike cerebral edema, ordinary mountain sickness involves no disruption of blood circulation in the brain".
Whether mountain sickness involves disruption of blood or not is irrelevant as long as it's symptoms are same as cerebral edema.

Hope this clarifies your doubt nks2611

That makes sense
Thanks coolnuts

Sent from my HM 1S using GMAT Club Forum mobile app

If you negated the letter E you will see that it can not be the answer.

If most people do not need special treatment to recover form mountain sickness than it is dangerous !!! But if they need a special treatment to recover from mountain sickness but the treatment is not effective against cerebral edema , than it will also be dangerous. So the argument does not depend on that.

Hope it's clear !

I choose A. If the treatment of two kinds of sickness is the same, cerebral edema wouldn't be that dangerous at high altitude because people would cure it as cure normal mountain sickness.

I think C is the correct option.
It clearly differentiates the line of severity. One can revover from Mountain sickness, but can not recover from CE.

CONCLUSION will break-down if you negate this.

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I did not get how A is the answer.
Any one pls give some explanation.

I will try answering the question. The more I think about this question, the deeper it gets. I am having fun exploring it. Here it goes:

1. The first trap is the relation between the premise and conclusion.
Conclusion: Cerebral Edema (CE) is especially dangerous at hight altitudes.

There are 2 relations in this comparison:
a. That the cause of the two diseases - mountain sickness (MS) and CE are similar - because conc states that CE severe with oxy supply scarcity same as MS.
b. CE varies from MS in its recovery - very subtle but the word especially in the conc and 1st line - "MS most ppl can recover" denote it.

Prethinking: Anything that states CE is different from MS in the way of recovering - say treatment or the affected severity is correct.

A & C are strong contenders.

2. Why C is wrong:
Sufficient vs necessary condition of Assumption:

C - Unlike cerebral edema, ordinary mountain sickness involves no disruption of blood circulation in the brain.

We need to say that recovery from CE is more difficult than MS - but disruption of blood circulation to brain not necessary condition.
There could be 100 other reasons why CE is dangerous than MS. This could be a strengthen answer but not assumption answer.

A - fits perfectly - The treatment for ordinary mountain sickness differs from the treatment for cerebral edema.
Though it does not say treatment of CE more tedious or something like that could have been helpful,
but saying that the 2 diseases treatments are different is sufficient.

Beautiful question, enjoyed breaking it down.

After answering the question wrong in my first attempt, I could see why A is the correct answer.

Let's go step by step.
The conclusion is that Cerebral Edema is especially dangerous at high altitudes

Reason/ Premise - Symptoms of Celebral Edema and Ordinary Mountain Sickness are similar and Celebral Edema needs to be treated in the beginning itself.

Most of us must have gotten confused b/w option A and E.

Let's see Option A:
The treatment for ordinary mountain sickness differs from the treatment for cerebral edema.
If we negate the statement, we get that the treatment of the two is the same, meaning that if irrespective of the disease, you will get treated. This shatters our conclusion which says that Celebral Edema is dangerous at high altitudes. Looks super good!

Let's see Option E:
Most people who suffer from ordinary mountain sickness recover without any special treatment.
This seems fair and something that was perhaps assumed in the situation. But how does it affect the conclusion?

Since we have a much better option, the answer is option A.

To make the conclusion true that “cerebral edema is especially dangerous at high altitudes”
The below point came in mind:-
cerebral edema can not be recovered or treated at high altitudes quickly.
( if it can be recovered automatically or using first aid or using simple tools then it would not have been dangerous)

What option can be necessary and keep the conclusion absolutely true ?



Absolutely, if the treatment is same , the person suffering from cerebral edema could have been recovered quickly.


We don’t know . maybe it needed a special tool or special machine or some special medicine or using any therapy. It is not a necessary condition to keep the conclusion true. Our intention is to find what can make cerebral edema is especially dangerous at high altitudes.

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