Q27:

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.

 In order to evaluate the argument, it would be most helpful to determine which of the following?

1. Whether zinc is effective only against colds, or also has an effect on other virally caused diseases
2. Whether there are remedies that do not contain zinc but that, when taken orally, can reduce the duration of colds
3. Whether people who frequently catch colds have a zinc deficiency
4. Whether either the zinc gel or the lozenges contain ingredients that have an impact on the activity of the zinc
5. Whether the zinc gel has an effect on the severity of cold symptoms, as well as on their duration

我當時直覺就是B，后來分析了一下，覺得B很完美啊。B：是否有其他的治療方法但不含Zinc，口服，可以減少感冒時間。如果Yes，那么說明鼻子里含有cold viruses的結論是錯誤的，如果No，說明的確只有鼻子里才有cold viruses。

可是答案是D。我不能說D為什么就不對，但是和B比起來就覺得B更好些。請各位幫我分析一下啊，我的思路錯在哪里了啊。拗不過來了。

B. Whether there are remedies that do not contain zinc but that, when taken orally, can reduce the duration of colds

B doesn't say enough.  Let's say the statement in B is correct, what then if the same remedies can treat cold even better by applying nasally? Hence B is not good enough.

The focus of the argument here is between the two different zinc remedies.