The ancient Nubians inhabited an area in which typhus occurred, yet su

Question

The ancient Nubians inhabited an area in which typhus occurred, yet surprisingly few of their skeletons show the usual evidence of this disease. The skeletons do show deposits of tetracycline, an antibiotic produced by a bacterium common in Nubian soil. This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread. Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

Which of the following is an assumption on which the argument relies?

(A) The tetracycline deposits did not form after the bodies were buried.

Which of the following is an assumption on which the argument relies?

(A) The tetracycline deposits did not form after the bodies were buried.

(B) The diseases other than typhus to which the ancient Nubians were exposed would not be affected by tetracycline.

(C) Typhus is generally fatal.

(D) Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.

(E) Bread and beer were the only foods eaten by the ancient Nubians which could have contained tetracycline.

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ChiranjeevSingh · Accepted Answer

Let me explain why option A is wrong.

First of all, the following version of A would be correct:

The tetracycline deposits did not form from the tetracycline that entered into the bodies after the bodies were buried.

This version is correct because the negation of this option would mean that the tetracycline deposits we see today are the result of the tetracycline that entered into Nubians' bodies after they were buried. So, this tetracycline could not have prevented typhus while they were living since it entered after their bodies were buried.

However, the original option A is wrong because the negation of the original option A means that the tetracycline deposits formed after the bodies were buried. We don't have a problem with this; the deposits could have formed after the death of those people; we just need tetracycline to be in their bodies while they were alive. Rather, "deposits" are expected to form over a long period of time. Thus, the fact that they formed after the death of Nubians doesn't mean that tetracycline was not there in the bodies of Nubians while they were alive. Tetracycline could easily have been in their bodies while they were alive, and then once they died, deposits formed over a long period of time. Simple!

kuttingchai · Answer

Will vote for D because

Question type : Assumption (Strengthen the conclusion)

conclusion : tetracycline in food explains the low incidence of typhus among ancient Nubians.

Premise 1: skeletons do show deposits of tetracyclinean antibiotic produced by a bacterium common in Nubian soil.

Premise 2: This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread.

A. The tetracycline deposits did not form after the bodies were buried.
--> one of the premise already state that "skeletons show the usual evidence of this disease", so option A cannot be true

B. The diseases other than typhus to which the ancient Nubians were exposed would not be affected by tetracycline.
--> Out of scope nothing talking about another diseases

C. Typhus is generally fatal.
--> Doesnot strengthe the conclusion.

D. Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.
--> Provide additional evidence that will strength the conclusion. If the Tetracycline which acts as antibiotic is not destroyed in the process of making bread or beer, then we can correctly conclude that 
tetracycline in food probably explains the low incidence of typhus.
Correct

using ANT
Tetracycline is rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.
This clearly contradicts the conclusion, if Tetracycline doesnot act as antibiotic, then incidence of typhus would have been higher

E. Bread and beer were the only foods eaten by the ancient Nubians which could have contained tetracycline. 
--> wrong because thay cannot be only source as they were made from grains and bacterium flourished on the dried grain.

aligol · Answer

such a tricky question :shock:

Now, I think D is the correct one. Both A and D look correct, but what makes D the correct one, is the part that says "Thus, tetracycline in their food probably explains..."

tuanquang269 · Answer

Use negate technique for choice A: The tetracycline deposits FORMED after the bodies were buried.

If the tetracycline formed after the bodies were buried, this kind of antibiotic still did not relate to the tetracycline that produced by bacteria in beer and bread.

ChrisLele · Answer

The ancient Nubians inhabited an area in which typhus occurred, yet surprisingly few of their skeletons show the usual evidence of this disease. The skeletons do show deposits of tetracycline, an antibiotic produced by a bacterium common in Nubian soil. This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread. Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

Which of the following is an assumption on which the argument relies?
Conclusion- tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

(A) The tetracycline deposits did not form after the bodies were buried.

(B) The diseases other than typhus to which the ancient Nubians were exposed would not be affected by tetracycline.- irrelevant, we are concerned whether tetracycline in food explains the low incidence of typhus

(C) Typhus is generally fatal.- irrelevant

(D) Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.

(E) Bread and beer were the only foods eaten by the ancient Nubians which could have contained tetracycline.- irrelevant, the argument claims tetracycline in food

I was down to options A and D and chose option A.

A on negation, The tetracycline deposits did form after the bodies were buried.
D on negation, Tetracycline is rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.
Both options seem like assumptions to me.

AjiteshArun , GMATNinja , MagooshExpert , GMATGuruNY , VeritasPrepBrian , MartyTargetTestPrep , DmitryFarber , VeritasKarishma , generis , nightblade354 other experts - please enlighten

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adityapagadala · Answer

IMO D

Because on negating A we get. The tetracycline deposits did form after the bodies were buried (Nothing told about scenario before bodies were buried). this implies two statements.
1) Tetracycline formed only after bodies were buried
2) Tetracycline formed both before and after bodies were buried

1 inverses the conclusion but 2nd does not inverse the conclusion.

Hence D

SVaidyaraman · Answer

Facts: few of the skeletons of Nubians show the usual evidence of the disease typhus even though they inhabited an area in which typhus occurred,. But their skeletons show deposits of tetracycline, an antibiotic produced by a bacterium common in Nubian soil. This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread.

Missing Information:There is no alternate explanation to what is shown in bold or it is not falsified, such as Tetracycline being rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.

Conclusion: Thus, tetracycline in their food probably explains  the low incidence of typhus among ancient Nubians.

Choice D is the best match for the missing information.

Choice A seems very close. To eliminate one of the two, we have to focus on the reason for the conclusion. It is shown in bold. It means that the author believes that tetracycline was their in their food and this would eliminate A because choice A is more a premise. So actually attacking author's argument is showing tetracycline in the food is not responsible for the low incidence of the disease.
So the assumption of D saying that the tetracycline in the food is effective, is required.

madvarsha14 · Answer

There is one more point, which makes A weak as an assumption. If tetracycline deposited from the soil into the skeletons of these bodies, it still does not explain why only " few of their skeletons  showed the usual evidence of typhus. After all, the ancient nubians inhabited in the area where typhus occurred, making them more susceptible to the disease. Most of them would have incurred the disease when they were alive. Typhus would invade their bodies when they were alive.

Skywalker18 · Answer

The ancient Nubians inhabited an area in which typhus occurred, yet surprisingly few of their skeletons show the usual evidence of this disease. The skeletons do show deposits of tetracycline, an antibiotic produced by a bacterium common in Nubian soil. This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread. Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

Which of the following is an assumption on which the argument relies?

(A) The tetracycline deposits did not form after the bodies were buried.

Which of the following is an assumption on which the argument relies?
Conclusion- tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

(A) The tetracycline deposits did not form after the bodies were buried.

(B) The diseases other than typhus to which the ancient Nubians were exposed would not be affected by tetracycline.- irrelevant, we are concerned whether tetracycline in food explains the low incidence of typhus

(C) Typhus is generally fatal.- irrelevant

(D) Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.

(E) Bread and beer were the only foods eaten by the ancient Nubians which could have contained tetracycline.- irrelevant, the argument claims tetracycline in food

I was down to options A and D and chose option A.

A on negation, The tetracycline deposits did form after the bodies were buried.
D on negation, Tetracycline is rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.
Both options seem like assumptions to me.

AjiteshArun  ,  GMATNinja  ,  MagooshExpert  ,  GMATGuruNY  ,  VeritasPrepBrian  ,  MartyTargetTestPrep  ,  DmitryFarber  ,  VeritasKarishma  ,  generis  ,  nightblade354  other experts - please enlighten

nightblade354 · Answer

The ancient Nubians inhabited an area in which typhus occurred, yet surprisingly few of their skeletons show the usual evidence of this disease. The skeletons do show deposits of tetracycline, an antibiotic produced by a bacterium common in Nubian soil. This bacterium can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread. Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

Which of the following is an assumption on which the argument relies?

(A) The tetracycline deposits did not form after the bodies were buried.

Which of the following is an assumption on which the argument relies?

(A) The tetracycline deposits did  not  form after the bodies were buried.

Skywalker18 , Our conclusion is that tetracycline explains why there was a low incidence of typhus. Our premises give an indication as to why we discovered that tetracycline was in use by these people. (A) tries to attack a premise by saying that the buildup occurred after death, but does this destroy our argument? For one, another premise does say that tetracycline is in the soil, so that would actually strengthen our argument on that front. Second, not taking this into account, just because the buildup occurred after doesn't mean that the people didn't take it. It is equally as likely that they ate the grains even if the buildup wasn't on the bones. We would need another assumption about how tetracycline only builds up on bones if it is consumed. Our premise is being used to show a presence of an item, but just because the presence is questioned doesn't mean that it wasn't effective or in use.

MartyTargetTestPrep · Answer

They could both be assumptions, but, of the two, only (D) is necessary for arriving at the conclusion. If (A) is not true, the argument still has some decent support for the conclusion that the ancient Nubians consumed tetracycline when they consumed food. If (D) is not true, then the conclusion is virtually unsupported.

It's a funny question though, I have to admit, because the part about the bone deposits is part of the support for the conclusion, and that support does not work without (A).

AndrewN · Answer

One of the reasons I prefer a "missing link" strategy for CR assumption questions, as opposed to the more popular negation technique, is that I get to leave everything alone and simply drop in a line wholesale to test whether I can go from premise to conclusion seamlessly. Try (A) and (D), respectively, in this manner:

PASSAGE (premise):  This bacterium     can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread.

ANSWER: A. The tetracycline deposits did not form after the bodies were buried.

PASSAGE (conclusion):  Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

It seems a little strange to discuss the Nubian diet as a premise, then insert information about tetracycline and skeletal remains, for which we have to reach back further in the passage to qualify, and then return to the idea of  food  being a primary determinant in  the low incidence of typhus among ancient Nubians.  I would not write off the answer, but I cannot say that X (the premise) connects to Z (the conclusion) through it. I would  yellow light  the answer in my first pass, but I would be hoping for a better, more fitting bridge to connect the two lines from the passage. Try (D) out in the same way:

PASSAGE (premise):  This bacterium     can flourish on the dried grain used for making two staples of the Nubian diet, beer and bread.

ANSWER: Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer.

PASSAGE (conclusion):  Thus, tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

Wow, if that is not a perfect bridge or "missing link," then I am not sure what more we could want. The premise mentions the  diet  of the ancient Nubians, the answer choice rules out the possibility that an active antibiotic compound suspected to be a part of that diet would be  rendered ineffective  prior to consumption, and then the conclusion about  food  follows. This is a  green light  answer, one that we cannot find fault with.

Between (A) and (D), then, the latter is  directly  related to the premise and the conclusion that follows, so it is the safer bet, and we should choose it. The order in which the sentences are presented in the passage is crucial to the process I have outlined. Anyway, I hope that helps. Just remember that when you find friction, you are probably not pursuing the path of least resistance, and in Verbal, that often translates into a wrong answer.

Good luck with your studies.

- Andrew

aletheia225 · Answer

Wrong. Not so simple, as it turns out.

If the T deposits formed after the fact, the argument loses its basis for maintaining that T was in the food supply. It may have been, but the argument's capacity to make such a claim, and therefore maintain that its anti-bac activity is responsible for low disease incidence, is rendered hollow. The argument could maintain that T is responsible on the basis of its having anti-bac effects and possibly being in the food supply because it flourishes on the grain used to make the food staples, but that's not what it does. It works from the premise that the T in the skeletons was T from when the skeletons were those of living people.

(A) is a necessary assumption.

ChiranjeevSingh · Answer

I see. So, according to you, this official question has two correct options?

PReciSioN · Answer

Brilliant!  ChiranjeevSingh

But in option-D, even if tetracycline is rendered ineffective by the process in preparing the food items, as long as the bacteria flourishing in those grains (and so in the food) survives the cooking process, can it not simply produce tetracycline again? In this case D would not be necessary. 
  GMATNinja  ,  KarishmaB  . Could you also comment on this please? Thanks

GMATNinja · Answer

That's a stretch because the passage tells us that the bacterium can flourish on the DRIED grain used for making beer and bread. In order for your scenario to work, we have to assume that the bacterium can flourish not only (1) on the dried grain  used  for beer and bread but also (2) in the beer and bread itself.

In other words, you're introducing a new argument: that tetracycline can form in finished beer and bread. Even if that were true, it is NOT the same argument made by the author -- the author's argument is that the tetracycline forms on the dried grains that are used as  ingredients  for the beer and bread.

Choice (D) might not be required for your new argument, but it IS required for the author's argument.

I hope that helps!

egmat · Answer

Let's break down the argument:

The author presents a puzzle: Ancient Nubians lived where typhus was common, but their skeletons rarely show typhus evidence. Here's the explanation offered:

Nubian skeletons contain tetracycline (an antibiotic) 
 This tetracycline came from bacteria that grew on grain 
 Nubians used this grain to make bread and beer (dietary staples) 
  Conclusion:  The tetracycline in their food explains the low typhus rates

Now here's the key question you need to ask:  What gap exists between the premises and conclusion?

Notice the logical jump happening here. The argument moves from "tetracycline was present in the grain" directly to "tetracycline in their food protected them from typhus." But think about what happens between these two points—the grain goes through a transformation process. It gets baked into bread and fermented into beer.

Here's the critical insight:  For this argument to work, the food preparation process can't destroy the tetracycline's antibiotic properties.

Think about it this way: If baking bread or brewing beer destroyed the tetracycline's effectiveness, then consuming these foods wouldn't have provided any disease protection whatsoever. The entire causal chain collapses.

This is exactly what  (D)  addresses: "Tetracycline is not rendered ineffective as an antibiotic by exposure to the process involved in making bread and beer." This assumption bridges the gap between "tetracycline in grain" and "tetracycline protecting Nubians."

Why the other answers don't work:

(A)  Post-burial formation - This addresses when the deposits formed, but not whether the tetracycline was effective during the Nubians' lives. 
  (B)  Effects on other diseases - The argument is specifically about explaining low typhus rates. What happens with other diseases is outside the scope. 
  (C)  Typhus being fatal - The severity of the disease doesn't affect whether tetracycline could prevent or treat it. 
  (E)  Bread/beer being the only sources - This is too extreme. The argument only needs these foods to contain  enough  tetracycline to be protective, not that they're the exclusive sources.

For the complete framework on how to systematically identify assumptions using the negation test technique, plus the underlying patterns that apply across all assumption questions, you can check out the  step-by-step solution on Neuron by e-GMAT . You'll also discover detailed explanations with practice quizzes for many other official CR questions  here on Neuron , including analytics that track your performance across different question types.

Hope this helps clarify the reasoning! Let me know if you have any questions.

rak08 · Answer

ChiranjeevSingh

Is it correct if I thought this instead

I felt the conclusion is on "X->inhibiting->Y",
so the assumption which negates that is what we are looking for 
so i eliminated A

guddo · Answer

Yes, I'd say, your instinct is basically right: when the conclusion is “tetracycline in food explains low typhus,” the argument needs the link  tetracycline stays effective -> it can inhibit typhus . So an assumption that would  break  that link is a good way to spot the correct choice.

But eliminating (A) from that logic is correct: (A) is about whether the deposits formed after burial. Even if (A) were false, it would not necessarily break the “tetracycline in food could have inhibited typhus” link, because the tetracycline could still have been consumed in life.  So (A) is not required.

The ancient Nubians inhabited an area in which typhus occurred, yet su

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