One summer, floods covered low-lying garlic fields situated in a region with a large mosquito population. Since mosquitoes lay their eggs in standing water, flooded fields would normally attract mosquitoes, yet no mosquitoes were found in the fields. Diallyl sulfide, a major component of garlic, is known to repel several species of insects, including mosquitoes, so it is likely that diallyl sulfide from the garlic repelled the mosquitoes.

Which of the following, if true, most strengthens the argument?


Diallyl sulfide is also found in onions but at concentrations lower than in garlic.

The mosquito population of the region as a whole was significantly smaller during the year in which the flooding took place than it had been in previous years.

By the end of the summer, most of the garlic plants in the flooded fields had been killed by waterborne fungi.

Many insect species not repelled by diallyl sulfide were found in the flooded garlic fields throughout the summer.

Mosquitoes are known to be susceptible to toxins in plants other than garlic, such as marigolds.

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情景：洪水覆盖了蒜地。因为蚊子喜欢在静水中产卵，所以洪水留下的水坑一般会吸引到很多蚊子。但是，现在洪水留下的水坑里没有蚊子。大蒜中的烯丙基化硫被认为可以防蚊。因此，是大蒜中的烯丙基化硫导致水坑中没有蚊子的。

推理：本题的前提中两件事具有时间关联，结论中具有因果关系，故而是相关因果推理。
前提：“大蒜中的烯丙基化硫”和“洪水留下的水坑里没有蚊子”具有相关关系
结论：大蒜中的烯丙基化硫导致水坑中没有蚊子

选题方式：相关因果推理有四个评估方向，简而言之，即，要么同时提及“大蒜中的烯丙基化硫”和“洪水留下的水坑里没有蚊子”，要么给“洪水留下的水坑里没有蚊子”另一个原因。

选项分析：

A选项：烯丙基化硫也发现在洋葱中，但是没有大蒜中的浓度高。本选项只提及了烯丙基化硫，没有提及蚊子。

B选项：在发洪水的年份中蚊子的数量比之前少很多。本选项可以给“洪水留下的水坑里没有蚊子”另一个原因，即，不是因为烯丙基化硫，而是因为蚊子数量本身就很少。

C选项： 在夏天结束的时候，大部分的大蒜植被都被水生真菌杀死了。大蒜被杀死并不代表不含有烯丙基化硫，所以本选项无关推理文段中的因果。

D选项：Correct. 那些不被烯丙基化硫影响的昆虫在水中存活了。若不被烯丙基化硫影响的昆虫也死了，则其表示“大蒜中的烯丙基化硫”和“洪水留下的水坑里没有蚊子”并没有必然关系。属于CQ1：相关性存在问题。

E选项：蚊子除了容易被大蒜中的毒素影响外，还会被其它植物中的毒素影响，比如金盏花。本选项给出的是蚊子的性质，没有提及推理文段中的因和果。

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