Logical reasoning PrepTest 141 · Section 2 · Question 8

Incorrect. Other jellyfish with similar retinas could be used to strengthen this argument if these other jellyfish also don't need anything more than the ability to see prominent features.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
One part of a box jellyfish's eye could see fine details, but another prevents them from seeing anything other than prominent features. Therefore, eyes adapt only to the needs of the organism.

Answer Anticipation:
The conclusion brings up the needs of the box jellyfish, but there's no indication of what those needs are in the premises, and whether the retinas that can only distinguish prominent features are adapted to hit those needs. Maybe the jellyfish doesn't need to see even prominent features because it has very strong other senses.

Answer Explanation:
This answer connects the needs of the box jellyfish to what its eye is capable of seeing. If a box jellyfish needs to see fine details, then the argument falls apart.

Key Takeaway:
New terms that show up in the conclusion of an argument are always where you should start when looking for flaws in arguments. It's almost always the case that the argument has made a jump from some related concept to that new term.

Incorrect. The conclusion is about the needs of an animal, so any benefit beyond the base needs is out of scope.

Incorrect. This answer is trying to get you to think it explains why the lens can produce sharp images with fine detail, therefore being necessary for the argument. However, there are a couple issues with that. First, this is only one explanation of why that could have happened, and since there are other potential explanations, this one isn't necessary. Second, while there does need to be an explanation for the lens, the argument doesn't have to establish what it is.

Incorrect. If jellyfish primarily use some other sense to catch prey, the argument could still work. In fact, since their eyesight doesn't appear to be all that developed, it might actually help the argument if they use other senses to catch prey, as then good eyesight would be less needed.