OG-93 请教nn们，a b e选项是否无关呢？

93. Dental researchers recently discovered that tooth-brushes can become contaminated with bacterial that cause pneumonia and strep throat. They found that contamination usually occurs after toothbrushes have been used for four weeks. For that reason, people should replace their toothbrushes at least once a month.

Which of the following, if true, would most weaken the conclusion above?

(A) The dental researchers could not discover why toothbrush contamination usually occurred only after toothbrushes had been used for four weeks.

(B) The dental researchers failed to investigate contamination of toothbrushes by viruses, yeasts, and other pathogenic microorganisms.

(C) The dental researchers found that among people who used toothbrushes contaminated with bacterial that cause pneumonia and strep throat, the incidence of these diseases was no higher than among people who used uncontaminated toothbrushes.

(D) The dental researchers found that people who rinsed their toothbrushes thoroughly in hot water after each use were as likely to have contaminated toothbrushes as were people who only rinsed their toothbrushes hurriedly in cold water after each use. C

(E) The dental researchers found that, after six weeks of use, greater length of use of a toothbrush did not correlate with a higher number of bacterial being present.

OG解释：

Since the recommendation is based on the discovery that bacterial contamination occurs after about four weeks,

the researchers’ inability to discover why contamination takes that long to appear does not weaken the recommendation (choice A),

nor does their failure to investigate other forms of contamination (choice B),

nor does the discovery that contamination does not worsen after six weeks (choice E).

答案选c理解但是不明白abe选项应该是有关但无法削弱，或是根本就是无关的呢？

把我对题目的理解也贴出来：

after four weeks ->contamination occurs

contaminated with bacterial ->pneumonia and strep throat

结论： replace their toothbrushes at least once a month.

选项C为有因无果的削弱，选项D加强。

个人感觉，A很明显的无关。但是BE呢？请教NN，

  我觉得ABE都有关, 但是没有起到直接削弱的作用.我觉得C说得特别顺眼和有道理.

A,B,  我觉得有点象EVALUATION, 但C 是EVALUATION 的结果.E有削弱, 但没有C 明显和直接.

    我只是参与讨论,水平不高, 还请大家指教.

谢谢楼上几位的参与！

我现在的理解是：文章说因为牙刷用了四个星期后感染细菌，所以要每个月换一次。

A:为什么四星期后会感染（反正感染了），B:其他致病源（感染细菌就够了），E:六周以后会不会恶化（说的是四个星期），

都与推理过程无关。请各位指教啊！