PrepTest 111, Section 4, Question 22
Multiple sclerosis is an autoimmune disease: white blood(94 more words not shown)
Which one of the following(11 more words not shown)
- AGamma interferon stops(7 more words not shown)
- BAdministering gamma interferon(15 more words not shown)
- CMedical researchers have(18 more words not shown)
- DIt has now(13 more words not shown)
- EThe drug now(14 more words not shown)
Reading the argument
That treatment went in the wrong direction. The scientists tried an antiviral substance because they suspected a viral trigger, yet every patient in the experiment became dramatically worse.
A failed treatment can still teach us something. The result gives us a reason to investigate whether gamma interferon contributes to the problem rather than fixes it. It doesn't, by itself, tell us every effect the substance has or prove why the patients worsened.
What we’re looking for
We're asked for the statement least compatible with this account. I'd expect a choice making gamma interferon sound helpful for multiple sclerosis, because that would be hardest to reconcile with what happened in the experiment. The other four choices only need to fit the account; they don't all have to be established by it.
Working the answers
- ACorrect
The passage says white blood cells attack the protective myelin sheath. A says gamma interferon stops those cells from producing compounds that destroy myelin. That sounds like blocking the very damage associated with the disease. Why, then, did giving patients gamma interferon make them dramatically worse?
This is the strongest tension among the choices. It isn't an absolute impossibility: a substance could have one helpful effect and another harmful effect. But the task asks which statement is least compatible, and A describes a protective effect where the experiment instead produced serious worsening.
- B
This concerns people who don't have multiple sclerosis. The experiment described patients who do. An increase in white blood cells in the other group doesn't contradict the patients' worsening, and nothing in the account says gamma interferon cannot increase white blood cell numbers. We don't need to establish B as true to see that it can fit.
- C
A sharp rise in gamma interferon around attacks fits the concern raised by the experiment. It would be consistent with the substance having some connection to worsening symptoms. That timing alone wouldn't prove the substance causes attacks, but it certainly doesn't clash with the reported result.
- D
This would fit a history in which scientists initially suspected chronic viral infections and later found reason to move away from that suspicion. The passage reports an early hypothesis, not an established fact that most patients have chronic viral infections. Later evidence against that hypothesis is compatible with the account.
- E
If administering gamma interferon made patients worse, a treatment that inhibits its activity would make sense as a direction to investigate. The passage doesn't prove that this must be how the successful drug works, but the explanation is compatible with both the failed experiment and the eventual successful treatment.
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