Necessary AssumptionDiff: Easy
Logic Breakdown
Passage Summary: Doctors thought a drug worked because vertigo got shorter after it was released, but when the drug supply ran out for a few months, the vertigo duration didn't go back up, leading the author to claim the drug is useless.
Conclusion: The drug in question does not actually reduce the length of vertigo episodes.
Reasoning: During a three-month period when the drug was unavailable, the average duration of vertigo episodes did not change compared to when the drug was available.
Analysis: The author is making a causal claim based on a lack of change during a temporary shortage. To reach this conclusion, the author must assume that a three-month window is a sufficient amount of time for the 'true' duration of vertigo to reappear if the drug were actually working. If the drug has long-lasting effects that persist after one stops taking it, or if the 'average duration' is a metric that shifts slowly over years, then the three-month shortage wouldn't necessarily show a change even if the drug were effective. Look for an answer that addresses this timing gap or the persistence of the drug's effects.
Conclusion: The drug in question does not actually reduce the length of vertigo episodes.
Reasoning: During a three-month period when the drug was unavailable, the average duration of vertigo episodes did not change compared to when the drug was available.
Analysis: The author is making a causal claim based on a lack of change during a temporary shortage. To reach this conclusion, the author must assume that a three-month window is a sufficient amount of time for the 'true' duration of vertigo to reappear if the drug were actually working. If the drug has long-lasting effects that persist after one stops taking it, or if the 'average duration' is a metric that shifts slowly over years, then the three-month shortage wouldn't necessarily show a change even if the drug were effective. Look for an answer that addresses this timing gap or the persistence of the drug's effects.
Passage Stimulus
Passage Redacted
Unlock Full Passage13.Which one of the following is an assumption required by the argument?
Correct Answer
A
Answer A supplies the missing bridge: if the drug made a difference, a three‑month shortage would have produced a significant change in the average duration. That is exactly the conditional the argument needs to apply a no‑change observation to conclude no effect. Negation test: If a shortage would not have caused a significant change even when the drug does work, then the observed stability during the shortage gives no basis to conclude the drug has no effect. The argument collapses without A.
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