The prehistoric fish Tiktaalik is the earliest known animal with fingers. Since variations were so great among prehis...

tomgbean on December 31, 2019

A and D

Please explain why A and D are incorrect.

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AndreaK on December 31, 2019

Hi @tomgbean

This is like our last most strongly supported question! For future reference for others as well, here is my take again on how to approach this question type:

This stem is asking us which one of the following is most strongly supported. I actually think this is one of the trickiest question types, because it doesn't go so far as to mean must be true. Therefore, the right answer might require some assumptions. But again, we're not trying to prove that something MUST be true, so that's okay...instead, we are trying to identify which scenario from the answer choices is most supported by the limited evidence we are given in the stimulus. So, you're going to want to look for an answer choice that lines up with as much of the information given in the stimulus as possible, because that's what we are basing our reasoning on to say an answer choice is "most strongly supported."

I’ll expand on this a little bit as well. Most strongly supported questions are still similar to must be trues, especially in that they also prefer weaker answer choices. Just like when trying to prove that something must be true, when you are trying to prove that something is strongly supported, you want to have a lower standard that’s easier to prove. Proving that circumstances entail “all,” “anything,” “never” or “only” is a higher bar than proving “some,” or as I like to think of it, at least one. Because it’s easier to prove or support the idea that something happens sometimes, as opposed to every time, right?

So, unless they really are strongly supported by the evidence (which of course is possible!) often, weak answer choices are safer bets and strong answer choices are trap answers, because they might be getting at the right idea, but worded too strongly. Please note, however, that this is not to say a strongly worded answer choice can’t be correct. It all depends on what the evidence given in the stimulus is, but when you read the problem, be thinking about how restrictive that evidence is. That should help you identify if your threshold should be higher or lower.

Okay! Hope that helps you get a firmer grasp on this question type. Let’s take that strategy into these answer choices.

A) This prehistoric fish is an ancestor to many land mammals, but that doesn’t really give us reason to believe it itself lived or moved on land. We’re talking about evolution here, so if that fish came before other land mammals, that was a longgggg time ago! Maybe he just moved his fingers on the ocean floor, and it took multiple “in between species” (think every ancestor that came between monkeys and humans, maybe?) before being up on land was ever in the picture.

D) This is an example of an answer choice that is overly restrictive. “No fish” is a strong threshold to have to meet. Do we have evidence that rules out this fish to land phenomenon for all other fish? This is a tricky answer choice because it’s hard to think of a real world example. But, for the sake of understanding, what if there was an ancestor to the turtle a few billion years ago that was considered a fish, but could also move on land, and didn’t have fingers? So, this answer choice isn’t strongly supported because the evidence we are given doesn’t address what is the case for all other fish and how they move, it only talks about one species.

Hope this helps! Feel free to follow up if you have any more questions.