Sometimes in flaw questions, I realize that the flaw is an incorrect negation (e.g. a --> b, ~a-->~b), however the answer choice will not explicitly say "incorrect negation"

Is one regular way of describing the conditional flaw of "incorrect negation" that "the argument assumes that the only way to get to 'b' is 'a'" or "fails to see that a is not the only condition to get to 'b'?"

I'm trying to see if i properly understand PT 49 - s4 #23

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The correct answer is A. I see why it is correct but I wonder if this answer choice makes an additional assumption that is not explicitly stated.

(A) says "failure to prove a claim"

We're only told that "these studies... seriously flawed in their methodology." We aren't explicitly told that therefore this experiment failed to prove the claim. Aren't we making an additional assumption that flawed methodology = failed to prove claim? Or even more, we're assuming that these independent scientists were can actually be trusted?

I can see why B, C, D, and E are incorrect. But aren't we making additional assumptions for (A)?

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https://classic.7sage.com/lsat_explanations/lsat-38-section-1-question-23/

Hi 7sage community,

I've been studying for the LSAT for almost a year now. Here's my history:

I took a 2.5 month course with Testmasters summer 2017 and studied for the December LSAT, scored a 161

I started studying again in January for the February LSAT and scored a 163.

(now) I started studying again in April for this upcoming June LSAT.

My target is 168 minimum, best case is low 170s. So:

Thanks so much for your help! Minor stressing recently..