PrepTest 112

[lcid:3547] Prep Test 112 LSAT — Logical Reasoning — S4 Logical reasoning

Question prompt

Twelve healthy volunteers with Remaining source text redacted.
Why the credited answer is right

Credited answer: E

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Facts

Valid or Flawed

NA

Question Type

Must Be True Questions

Stimulus Summary

Group 1 - Gene 1
Group 2 - Gene 2
Both groups - Standard diet, but with a high-cholesterol food
(Side note - High blood cholesterol is associated with heart disease risk)
Results - Group 1 had higher blood cholesterol; Group 2 didn’t

Answer Anticipation

This is an interesting Must be True question, as it sets up a medical study. Normally, that would mean that the study would demonstrate a correlation, the scientists would draw a causal conclusion, and we’d point out that it’s flawed because it has a Correlation/Causation flaw.
But that’s not what’s going on here, as we’re dealing with a Must be True question! So what can we learn from the normal pattern? That we should avoid answers that are absolutely causal - while the study here provides evidence that the gene had some impact on blood cholesterol, it doesn’t prove a causal relationship. And the link between cholesterol and heart disease is also presented as a correlation (“is associated with”), further driving us away from causality.
That said, we do have evidence that Gene 2 (don’t even try to memorize the name) in some way affects the absorption of cholesterol from the diet into the blood. We can’t say for certain, so we’re looking for a weaker answer, but let’s see if we can find one that says something about that link.

Answer choices

  1. A
    Approximately half the population Remaining source text redacted.
    Why choice A is not credited
    Group 1 saw their cholesterol increase, and Group 2 saw it stay the same - there’s no indication that any gene lowers cholesterol. Also, even if we say Gene 2 lowers cholesterol (which, again, we can’t say), we don’t know that half of the population has that gene. The study was split 50-50, but it doesn’t state that that mirrors the population.
  2. B
    Most of those at Remaining source text redacted.
    Why choice B is not credited
    We don’t know anything about the group of people who are at risk of heart disease - they could all have Gene 1, or Gene 2, or be a skewed mix, or an even mix. Additionally, in bringing in heart disease, this answer relies on both correlations in the stimulus, thus making it less supported.
  3. C
    The bodies of those Remaining source text redacted.
    Why choice C is not credited
    There’s no discussion of how Gene 2 works, so we can’t infer that this is how it happens. Maybe Gene 2 doesn’t excrete blood cholesterol but rather convert it.
  4. D
    The presence of the Remaining source text redacted.
    Why choice D is not credited
    Gene 1 was present in the group that saw their cholesterol go up, suggesting that they’re not at a lower risk of heart disease. Even then, this answer builds a correlation on a correlation, making it unsupported.
  5. E
    The presence of the Remaining source text redacted.
    Why choice E matches the stem
    This answer relies on a single correlation (not two, like other answers) to suggest that the correlated items may have a causal relationship. Correlation doesn’t prove causation, but it does support it. Those with Gene 2 didn’t see an increase in cholesterol when they ate high-cholesterol food while the group with Gene 1 did, suggesting that the gene might be the reason that cholesterol didn’t go up.

What this tests

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