注解版PREP解释中的又一矛盾？

PREP注解中说“过去完成时的分词结构在GMAT中是错误结构。having been done不能作为后置定语修饰先行词，应改为其对应的定从that have/have been done”，可154偏偏又选A，请高手指点下！谢谢
                

154．Some patients who do not respond to therapies for depression may simply have received inadequate treatment, having, for example, been prescribed a drug at a dosage too low to be effective or having been taken off a drug too soon.

(A) having, for example, been prescribed a drug at a dosage too low to be effective or having been

(B) having, for example, a drug prescription that was ineffective because the dosage was too low, or being

(C) as, for example, having too low of a dosage of a prescribed drug for it to be effective, or being

(D) when they have, for example, been prescribed too low a drug dosage to be effective, or were

(E) for example, when they have a drug prescription with a dosage too low to be effective, or been

up

同意三楼的！关注考平行就OK~

好像前面也回了给你的帖子，不是NN,因为我也在琢磨PREP SC呢，四月考~

感觉虽然PREP的SC很强调逻辑意思，但是有时候从意思去判断真的挺难，应该注重培养寻找更简单考点选答案的能力。

我也不行。慢慢琢磨。一起努力吧~