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?


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

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

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

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

Typhus is generally fatal.

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情景：努比亚人住在一个typhus经常发生的地方。但是他们很少患上这种病。他们的骨骼显示了tetracycline的沉淀物。努比亚人的主要食物啤酒和面包中含有可以产抗typhus的物质（tetracycline）的细菌。因此，食物中的tetracycline导致努比亚人不得病。

推理：
前提：“吃了含有tetracycline的啤酒和面包”和“不得病”之间存在正相关关系
结论：食物中的tetracycline导致努比亚人不得病

答案预估：

要么同时提及“吃了含有tetracycline的啤酒和面包”和“不得病”，要么给“不得病”另外一个原因。

选项分析：

A选项：努比亚人遇到的除掉typhus之外的传染病都不会被tetracycline所影响。其他传染病的情况不会影响typhus这种病的患病比率，所以本选项不能成为答案。

B选项：Correct. Tetracycline这种抗体不会在制作面包的过程中变得对于typhus无效。本选项削弱了食物中的tetracycline和typhus这种病之间的联系。如果Tetracycline会在制作过程总变得无效，那么就不会导致“果”的出现。

C选项：Typhus不会通过吞食被含有的病原体的面包和啤酒来传播。本选项描述的是Typhus这种病的传播方式，没有谈到“果”的问题，可以排除。

D选项：面包和啤酒是努比亚人的食谱中唯一可能含有Tetracycline的食物。无论面包和啤酒是不是唯一可能含有Tetracycline的食物，都不会影响Tetracycline可以导致不患typhus这种病。

E选项：Typhus一般是致死的。本选项描述的是Typhus这种病的性质，与其患病率没有联系。

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