This is back to basics for Necessary Assumption questions.

I read AC (B) and thought "that is so basic that there's no way it could be an answer for a hard NA question." That's exactly the point! NA questions are looking for an assumption that, no matter how small, is so basic that the argument would fail without it. It can be something that the author would say "hmmm. yeah i didn't think of that, but OF COURSE that has to be true for my argument." NA correct AC's can be basic as **** and still be correct; in fact, most likely will be correct.

Further, incorrect answers on NA questions will often be strengtheners, but just go TOO FAR to be bare-bones necessary for the argument. AC (E) goes too far. Sure, it strengthens... but it absolutely is not required to be true for the argument to survive. Aboriginal people could've used it for other things, and also used it for canoes. That's plausible, and doesn't undermine the argument in any significant way.

@DanielBednar this is the article that made it all click for me when I was endlessly confused: https://lsatdemon.com/resources/logical-reasoning/negating-assumption-negation

I've found the best way to think about them is to think what MUST be true? It doesn't have to be obvious, and prephrasing is often unhelpful because lots of times the answer choices will bring up small little assumptions that you just would've never even thought of. But what answer choice would make the author think "huh, yeah, didn't think of that, but yeah that's gotta be true or else my argument is screwed." That's the correct one.

This is a new cookie cutter flaw that keeps reappearing and that I keep getting wrong: just because I know something (bc it's given to me in the stimulus), doesn't mean the individuals/groups mentioned in the stimulus know the same thing.

The stem says "these results contradict," but doesn't say the scientists know that these results contradict. That's a flaw. JUST BECAUSE WE KNOW DOESN'T MEAN THEY KNOW.

Here, the conclusion was BROAD that the disclaimer serves no purpose whatsoever. But the only evidence it gives is one scenario where it doesn’t serve its purpose (when the email advocates for something illegal). What if the email doesn’t advocate for something illegal? We have to show that if it doesn’t advocate for something illegal, that the disclaimer still serves no purpose. That would allow us to draw this broad conclusion.