Hi Mazen!
While the passage does state that even trained officers often deviate from the procedures in cognitive interview training, this is does not mean we can support the idea that increases in complexity usually results in a reduction of information reliability across
all interview procedures! All we know is that in at least one example, increased complexity led trained officers to often deviate from procedures. We don't know how this might have impacted the reliability of witness recall, nor do we know if this applies to interview procedures as a whole, so this statement in (E) is much too strong for us to support.
Additionally, we even get a counterexample to a negative correlation between complexity and reliability in the passage. For example, when discussing hypnosis, the author states that this technique is "much less complex" but still "overall accuracy...is not generally improved with hypnosis; in fact, sometimes it may deteriorate."
Answer choice (A), on the other hand, is able to be supported by the same lines about trained officers deviating from procedures. Certainly, it seems the author is concerned about this "problem" and its impact, and while the author doesn't specify exactly why this is an issue, that's ok! The answer choice accounts for that in its non-specific language, only saying that "there is reason to worry the cognitive interview is less effective if police interviewers deviate from the procedures". Additionally, (A) is more specific and supportable than (E) in that it mentions cognitive interviews specifically, while (E) refers to "interview procedures" as a whole.
I hope this helps!
Kate