GWD7-Q17关于前提结论型和因果型

我看过FEIFEI的视频课件。也一直以来使用前提结论型和因果型来解题，感觉效果不错的，但是GWD7-Q17有疑惑：
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GWD7-Q17:

Of patients over 65 years old who survived coronary bypass surgery—a procedure widely prescribed for people with heart disease—only 75 percent benefited from the surgery.Thus it appears that for one in four such patients, the doctors who advised them to undergo this surgery, with its attendant risks and expense, were more interested in an opportunity to practice their skills and in their fee than in helping the patient.

Which of the following, if true, most seriously undermines the argument?

A. Many of the patients who receive coronary bypass surgery are less than 55 years old.

B. Possible benefits of coronary bypass surgery include both relief from troubling symptoms and prolongation of life.

C. Most of the patients in the survey decided to undergo coronary bypass surgery because they were advised that the surgery would reduce their risk of future heart attacks.

D. The patients over 65 years old who did not benefit from the coronary bypass surgery were as fully informed as those who did benefit from the surgery as to the risks of the surgery prior to undergoing it.

E. The patients who underwent coronary bypass surgery but who did not benefit from it were medically indistinguishable, prior to their surgery, from the patients who did benefit.

题目是说 65岁以上的人接受心脏搭桥手术，其中只有75%的人能够得到改善；剩下的1/4 人，都是医生昧着良心送入手术室的

我的疑惑是，到底是因果型，还是前提结论型？

我自己看的时候，觉得是用后半句，去解释前半句。也就是用医生昧良心来解释只有75%的成功。如果是这样来削弱的话，应该是

1.其他原因解释只有75%的成功。（他因解释）

2.医生昧良心成功率也不仅仅75%。（有因无果）

3. 医生没有昧良心但是成功率只有75%。（无因有果）

4. 医生没有昧良心而且成功率也没有仅仅75%。（无因无果）

而如果是按照前提结论来解题，思路是：否定结论即医生没有昧良心

正确答案E指医生不知道哪些病人会成功，哪些不会成功。正是用了前提结论的做法。

虽然选对了。但是这个疑惑一直在。不知道大家会不会觉得我是太死板了…还是求指导！