Logical reasoning PrepTest 104 · Section 4 · Question 24

Question prompt

Scientists, puzzled about the Remaining source text redacted.
Why the credited answer is right

Credited answer: C

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

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Argument Structure Questions

Stimulus Summary

Phenomenon - Patients who didn’t take penicillin end up developing penicillin-resistant bacteria
Explanation - They had mercury fillings, and the mercury-resistant genes are close to penicillin-resistant genes

Answer Anticipation

Very interesting. Unlike essentially every Argument Structure question on the exam, which asks about a statement in the stimulus, this one asks about an unstated assumption. We’ll have to see what that means as we work through it!
Taking a step back, this stimulus presents an explanation for a weird phenomenon. The phenomenon is that patients who didn’t take penicillin ended up with penicillin-resistant bacteria. The explanation? Something about genes and mercury - there’s a lot of science, so don’t get too wrapped up in it.
With that in mind, let’s look at the assumption - that some patients who take penicillin develop penicillin-resistant bacteria. That’s closer to the phenomenon than the explanation, so we should see if we can use that phenomenon to figure out the role of this assumption.
So the phenomenon is that some patients not taking penicillin developed the penicillin-resistant bacteria, and the assumption is that some patients who do take penicillin develop that bacteria. Well, the explanation there seems a lot more straightforward - the bacteria that are resistant to penicillin live in those patients, while the rest die, and so their development makes sense. Contrast that with the same resistant bacteria developing when there isn’t penicillin to cause that process to happen. This unstated assumption sets the baseline situation that makes the situation explained in the stimulus “puzzling.” Let’s find an answer reflecting that.

Answer choices

  1. A
    It is a hypothesis Remaining source text redacted.
    Why choice A is not credited
    First, the scientists in the stimulus set out to explain how patients not taking penicillin developed the resistant bacteria. Second, they believe they have found the explanation, which is less certain than saying that it’s conclusively proven.

  2. B
    It is a generalization Remaining source text redacted.
    Why choice B is not credited
    Just because people who take penicillin develop resistant bacteria doesn’t mean people who don’t take penicillin can’t develop resistant bacteria. That’s like saying since people who drink vodka get drunk, people who drink tequila don’t.

  3. C
    It is a point Remaining source text redacted.
    Why choice C matches the stem
    This answer highlights the role of the assumption in the question stem. It makes sense that people taking penicillin develop penicillin-resistant bacteria. What’s puzzling is when the same resistance develops in people who don’t take penicillin.

  4. D
    It is the tentative Remaining source text redacted.
    Why choice D is not credited
    First, there’s no hint of earlier research. Second, nothing in the stimulus suggests that penicillin-resistant bacteria can’t develop in people taking penicillin.

  5. E
    It is a generalization Remaining source text redacted.
    Why choice E is not credited
    The assumption in the question stem doesn’t deal with genetics at all, so this answer is incorrect.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 14%
  2. B 6%
  3. C Credited 68%
  4. D 3%
  5. E 10%

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