Great question - consider here the fact that the non-underlined portion "the perpetrators are..." comes right after a comma and right after the answer choice. So if you were to take E and say:

"in attributing a behavior to an allergy, the perpetrators..."

Well, this makes it sound as though the perpetrators are the ones who are attributing that behavior to an allergy. But the next part:

"the perpetrators are told..."

Doesn't make sense then. If I attribute my behavior to an allergy, I'm not being told anything...I'm both the attributor and the one being told, so I'm not telling myself. Plus the beginning of the sentence highlights the defense attorneys - they're logically the ones doing the attribution. So E, technically, is guilty of an improper modifier. Even broader, it just doesn't make logical sense (as is the case with most modifier errors when you really look at what makes them "wrong").

I also have problem with the tense. If we choose B, should we use "will" in the unconditional clause? "the perpetrators are in effect told that they will not be responsible for their actions?

Thank you.

Couple things on that tense:

1) You don't get a choice, since "are told..." is outside the underline, so part of good SC strategy is learning to live with some language that you don't love. The easiest way to make a question tough is to use correct language that you know people won't like.

2) In this case, "are" is actually much more logical than "will". The word "perpetrators" already signifies that someone committed a crime. So those actions have already happened, and the defense attorney is saying "but you can't be held responsible". If the sentence were to use "will", that's forward-thinking, so it's a prediction about the verdict ("I don't think you'll be found guilty") and not a general statement about the client's actual guilt ("yes you did this, but only because of an allergy - you are not responsible").