Though sucking zinc lozenges has been promoted as a treatment for the common cold, research has revealed no consistent effect. Recently, however, a zinc gel applied nasally has been shown to greatly reduce the duration of colds. Since the gel contains zinc in the same form and concentration as the lozenges, the greater effectiveness of the gel must be due to the fact that cold viruses tend to concentrate in the nose, not the mouth.
Which of the following, if true, most seriously weakens the argument?
AExperimental subjects who used the zinc gel not only had colds of shorter duration but also had less severe symptoms than did those who used a gel that did not contain zinc.
BThe mechanism by which zinc affects the viruses that cause the common cold has not been conclusively established.
CTo make them palatable, zinc lozenges generally contain other ingredients, such as citric acid, that can interfere with the chemical activity of zinc.
DNo zinc-based cold remedy can have any effect unless it is taken or applied within 48 hours of the initial onset of cold symptoms.
EDrug-company researchers experimenting with a nasal spray based on zinc have found that it has much the same effect on colds as the gel does.
解析：即使口服的zinc lozenge是治感冒的但是效果不好。目前發現了一個zinc的鼻用藥降低了感冒週期效果不錯。因為這個要包含了和原來一樣含量的zinc，所以這種新藥效果好是由於感冒病毒集中在鼻子裡。
讓你削弱的是並不是因為病毒在鼻子裡這個鼻用藥效果才好；
A選項：兩個藥之間的比較，一種含有zinc一種沒含，原文讓你比較的都含zinc而且含量一樣，只是想讓你說明是鼻子有病毒效果好，你只要得出的結論不是這個結論就行，所以A排除；
B感冒的機制還沒有確立，和原文無關，現在讓你削弱的是不是由於病毒在鼻子裡所有那個感冒藥好。如果改一下說鼻用藥機制好反而是削弱，削弱了病毒在鼻子裡呀。
C為了使藥可口，口服藥加了東西，削弱。間接表明，並不是病毒在鼻子裡而是因為口服的加了干擾成分使得口服的藥不如鼻用藥效果好。如果口服的沒加東西說不定效果一樣，就不能說明病毒在哪了；
D沒有加zinc的，原文兩個都加了，你說的是沒加的，無關；
E醫藥公司研究了一種鼻用藥效果和原文鼻用藥效果一樣，這不是加強嘛，可能病毒真在鼻子裡呢，你看這還有一種藥一樣用法效果也一樣。
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