The ancient Nubians inhabited an area in which typhus occurs, 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) Infectious diseases other than typhus to which the ancient Nubians were exposed are unaffected by tetracycline.

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

(C) Typhus cannot be transmitted by ingesting bread or beer contaminated with the infectious agents of this disease.

(D) Bread and beer were the only items in the diet of the ancient Nubians which could have contained tetracycline.

(E) Typhus is generally fatal.

Similar question from GMATPrep: LINK

Q30. The ancient Nubians inhabited an area in which typhus occurs, 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. Infectious diseases other than typhus to which the ancient Nubians were exposed are unaffected by tetracycline.
B. Tetracycline is not rendered ineffective as an antibiotic by exposure to the processes involved in making bread and beer.
C. Typhus cannot be transmitted by ingesting bread or beer contaminated with the infectious agents of this disease.
D. Bread and beer were the only items in the diet of the ancient Nubians which could have contained tetracycline.
E. Typhus is generally fatal.

Guys, both B and E are compelling. I'm leaning more towards E. If Typhus is not fatal, one might not expect to find traces of this disease in the skeletons. So, E is the main assumption on which this whole argument is based. B is the secondary assumption (B could be true only if E is true).

comments are welcome.
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Q30. The ancient Nubians inhabited an area in which typhus occurs, 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. Infectious diseases other than typhus to which the ancient Nubians were exposed are unaffected by tetracycline.
B. Tetracycline is not rendered ineffective as an antibiotic by exposure to the processes involved in making bread and beer.
C. Typhus cannot be transmitted by ingesting bread or beer contaminated with the infectious agents of this disease.
D. Bread and beer were the only items in the diet of the ancient Nubians which could have contained tetracycline.
E. Typhus is generally fatal.

Vineet, you are right. E is nowhere mentioned in the passage. But, that's why we are looking for an assumption. The first line says

"The ancient Nubians inhabited an area in which typhus occurs, yet surprisingly few of their skeletons show the usual evidence of this disease".

and the last one says

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

This clearly shows that the scientists assume that this disease was fatal, but still are surprised that only a few skeletons show the sign of the disease. They conclude that becuase pf tetracycline, only a few show signs of typhus. In other words, only a few contracted and died of typhus.
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Which of the following is an assumption on which the argument relies?

A. Infectious diseases other than typhus to which the ancient Nubians were exposed are unaffected by tetracycline.

Wrong: Other diseases out of scope.

B. Tetracycline is not rendered ineffective as an antibiotic by exposure to the processes involved in making bread and beer.

Correct: Negating this kills the argument, because the negation shows that tetracycline could not be the reason fire the low incidence of typhus.

C. Typhus cannot be transmitted by ingesting bread or beer contaminated with the infectious agents of this disease.

Wrong (good trap):
Whether typhus could be transmitted does not affect whether tetracycline prevented incidences of typhus.

D. Bread and beer were the only items in the diet of the ancient Nubians which could have contained tetracycline.

Wrong (good trap):
How Nubians obtained tetracycline does not affect conclusion.

E. Typhus is generally fatal.

Wrong: Fatality of typhus does not affect conclusion.

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