[求助]请教一道LSAT逻辑：lsat-0106-2-21题

Professor Chan: The literature department’s undergraduate courses should cover only true literary works, and not such frivolous material as advertisements.

Professor Wigmore: Advertisements might or might not be true literary works but they do have a powerfully detrimental effect on society—largely because people cannot discern their real messages. The literature department’s courses give students the critical skills to analyze and understand texts. Therefore, it is the literature department’s responsibility to include the study of advertisements in its undergraduate courses.

21.   Which one of the following is an assumption on which Professor Wigmore’s argument depends?

(A) Texts that are true literary works never have a detrimental effect on society.

(B) Courses offered by the literature department cannot include both true literary works and material such as advertisement.

(C) Students who take courses in the literature department do not get from those courses other skills besides those needed to analyze and understand texts.

(D) Forms of advertising that convey their message entirely through visual images do not have a detrimental effect on society.（B）

(E) The literature department’s responsibility is not limited to teaching students how to analyze true literary works.

答案是B。但我认为是E（由于Advertisements might or might not be true literary works ，即存在not be true literary works 的可能性，所以E：The literature department’s responsibility is not limited to teaching students how to analyze true literary works一定被假设了。而B我认为丝毫不贴边儿。）大家看呢？谢谢！！！

我本来是想同意E的,但是在分析过程中发现E不对,至少没有B好

原文: 前提1:Advertisements might or might not be true literary works but they do have a powerfully detrimental effect on society.

      前提2:The literature department’s courses give students the critical skills to analyze and understand texts

结论:Therefore, it is the literature department’s responsibility to include the study of advertisements in its undergraduate courses.

中间有2个隐含假设:1,通过广告可以获得critical skills .2. 其他方法(包括纯文学)不能获得.

对E取非: The literature department’s responsibility is  limited to teaching students how to analyze true literary works. 没有取非前,感觉挺象的,现在你看这个能削弱吗. 无关吧!. analyze 不是critical skill.

对B取非: Courses offered by the literature department can include both true literary works and material such as advertisement. 肯定是相关.不过我也没有看出来B怎么削弱.

请NN指点, 谢谢!

正确选项就是（E）；上面推出的第一个假设正确，第二个不正确。这里就是一个措施目的题，答案假设的类型是目的可能型假设。