PrepTest 113, Section 4, Question 13
When several of a dermatologist's patients complained of(56 more words not shown)
Each of the following, if(9 more words not shown)
- AMany telephones are(14 more words not shown)
- BContact between other(13 more words not shown)
- CMost of the(11 more words not shown)
- DTelephones are used(7 more words not shown)
- EThe complaints occurred(10 more words not shown)
Reading the argument
A rash on one side makes me wonder what touches that side. A pillowcase, for example, could be worth investigating. That isn't a diagnosis; it is a possible explanation of the uneven pattern.
The telephone turns out to touch the side with the rash in each case. That's a promising clue, but it doesn't settle the cause. What if the side reflects which hand the person usually uses? Someone might hold a phone with that hand and use the same hand to apply something else to the face. The phone could accompany the relevant activity without causing the rash itself.
What we’re looking for
The question is strengthen EXCEPT. Four answers will provide some additional support for the telephone explanation; one won't. We don't need every helpful answer to prove the diagnosis. The exception could be irrelevant rather than actively contradicting the dermatologist.
Working the answers
- A
This supplies a possible mechanism: an allergic reaction to the phone's plastic. We aren't told these particular patients have that allergy, so A doesn't establish the diagnosis. But identifying a material in many phones that can provoke a reaction makes the proposed cause more plausible. It supports the explanation and isn't the exception.
- B
This is less direct, but it helps with the concern about another source of contact. If other devices touch both sides equally, their contact is less well matched to a rash restricted to one side. The telephone's one-sided contact remains a better fit for that pattern.
B doesn't eliminate every alternative cause or show that equal contact must always produce identical effects. It only needs to add support, which it does by making competing devices less promising as an explanation of the asymmetry.
- C
Prolonged contact requires spending time on the phone. If a patient made one short call a week, we'd want more evidence before blaming extensive telephone contact. C tells us most of the patients' jobs require extensive use, making the proposed exposure more plausible. That supports the diagnosis without proving which part of the phone caused the rash.
- DCorrect
Lots of people use phones. What does that tell us about these patients' rashes? It doesn't connect phone use with the symptom, explain the one-sided pattern or establish prolonged use by the patients.
The popularity of a device isn't evidence that it caused a particular medical problem. D gives us a broad usage fact, while the other answers add something to the proposed relationship between contact and the rash. That makes D the exception.
- E
The complaints followed increased telephone use. That timing fits the idea that additional contact brought on the problem, so it adds support. It doesn't prove that nothing else changed at the same time, and it doesn't say rashes occur only when people use phones. The narrower timing relationship is enough to help.
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