PrepTest 131, Section 3, Question 16
A common genetic mutation that lowers levels of(53 more words not shown)
Which one of the following(8 more words not shown)
- ARestoring cathepsin C(10 more words not shown)
- BGenetic mutation is(9 more words not shown)
- CResearchers will soon(11 more words not shown)
- DPersons who do(16 more words not shown)
- EA person whose(13 more words not shown)
Reading the argument
The enzyme helps the body fight infections in the mouth, and the mutation lowers the enzyme's level. That makes it harder for someone to resist gum disease. Restoring the enzyme sounds promising.
But eliminate gum disease? What if poor brushing or flossing could still lead to it? Improving one part of the body's defenses doesn't automatically settle every way a disease might arise. The argument moves from a factor affecting resistance to a promise that correcting that factor will eliminate the disease.
What we’re looking for
My initial concern is whether the enzyme problem accounts for all the gum disease the researchers hope to eliminate. For the necessary assumption, we need a claim the author must accept for the proposed restoration to deliver that result. Keep the proposed treatment and its promised effect in view.
Working the answers
- A
The treatment doesn't have to be the only way to eliminate periodontitis. Suppose a different treatment could eliminate it too. That wouldn't stop enzyme restoration from working. The author needs this treatment to succeed, not all competing treatments to fail.
- B
A different cause of low enzyme levels wouldn't necessarily undermine the proposed treatment. Restoring the enzyme might work regardless of why its level was low. The author needs a connection between restoring the level and eliminating gum disease, not a claim that only one thing can lower the level.
- C
The conclusion says what will happen once restoration becomes possible. It doesn't say that will happen soon. Researchers could take a long time and the author's claim about the result, once achieved, would remain the same.
- D
This sounds close to the concern about other routes to gum disease, but notice that it concerns the genetic mutation rather than the enzyme level. Someone without that mutation could have low cathepsin C for a different reason and develop gum disease. Restoring the enzyme could still eliminate that person's disease, so the argument doesn't require everyone without the mutation to be free of it.
- ECorrect
This directly connects the proposed restoration with the promised result. If someone whose enzyme level had been restored to normal could still suffer from periodontitis, restoring it would not deliver the elimination the author claims. The argument therefore requires that restored levels rule out the disease. E addresses the treatment's success without adding A's claim that no other treatment could work.
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