Hi A,
Let's take these in reverse. In the stimulus we see a classic causal error where the author assumes that two things that happened simultaneously must be the result of one causing the other. It's a textbook causal mistake
Answer choice (E) is a good description of the causal error, and the kind of answer that even if you didn't see it as immediately correct, there's nothing wrong with it. We know now that it is correct, so I won't belabor the point further.
Answer choice (D) talks about the method of gathering data. You mentioned the Data Attack method of undermining causal assertions. the full description of that flaw is: "Show that a statistical problem exists with the data used to make
the causal statement." While I completely understand why (D) suggests a data problem when first examined (because it uses the word "data," of course!), when you look more closely, there is no direct attack on the data. There's nothing that says the study had problems or that there are other factors in play that might have affected the data. Instead, the answer suggests that the argument assumes the data gathering methods were reliable. That's not actually an attack on the data. Instead, it relates to an idea we talk about which is that unless otherwise noted, the LSAT allows authors to talk about surveys, studies, etc and assume they were done correctly. In other words, to attack a survey, study, research, and so on, you have to typically talk directly about a possible error. Otherwise, the argument is that it's ok to believe the data/results as [presented.
That may seem like a fine-line point here, but it's actually not. The general use of studies is fine; the question their use requires a specific reason. (D) doesn't have a reason.
This is a good one to think about and see what they did, because it's exactly the type of thing you could see again.
Thanks!