The new perfume Aurora smells worse to Joan than any comparably priced perfume, and none of her friends likes the smell of Aurora as much as the smell of other perfumes. However, she and her friends must have a defect in their sense of smell, since Professor Jameson prefers the smell of one of the world's foremost experts on the physiology of smell.
What this question is testing
The Setup
Joan does not like Aurora; her friends do not either. But Professor Jameson, a top smell expert, prefers Aurora. The author concludes Joan and her friends must have something wrong with their sense of smell.
Evaluate
For that argument to even make sense, Professor Jameson has to be a separate person from Joan's friends. Why? Because the stimulus says and Jameson does prefer Aurora. So if Jameson were one of Joan's friends, we would have a contradiction — one of her friends prefers Aurora, but none of her friends prefers Aurora.
To avoid that contradiction, Professor Jameson cannot be one of Joan's friends.
Goal
The right answer should be a strict logical consequence of the stimulus — not a leap or a reasonable guess. The Jameson-not-a-friend inference is forced.
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