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Source:GMAT Club Please provide your reasoning as well..TIA

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Source:GMAT Club
Please provide your reasoning as well..TIA
Healthy lungs produce a natural antibiotic that protects them from infection by routinely
killing harmful bacteria on airway surfaces. People with cystic fibroses, however, are unable
to fight off such bacteria, even though their lungs produce normal amounts of the
antibiotic. Since the fluid on airway surfaces in the lungs of people with cystic fibrosis has
an abnormally high salt concentration, scientists hypothesize that in high salt environments
the antibiotic becomes ineffective at killing harmful bacteria. Which of the following, if it
were obtained as an experimental result, would most decisively undermine the
scientists’ hypothesis?
A. Healthy lungs in which the salt concentration of the airway-surface fluid has been
substantially increased are able to reestablish their normal salt concentration within a
relatively short period of time.
B. The antibiotic produced by the lungs is effective at killing harmful bacteria even when salt
concentrations are below levels typical of healthy lungs.
C. The salt concentration of the airway-surface fluid in the lungs of people who suffer from
cystic fibrosis tends to return to its former high levels after having been reduced to levels
typical of healthy lungs.
D. The lungs of people who suffer from cystic fibrosis are unable to fight off harmful bacteria
even when the salt concentration is reduced to levels typical of healthy lungs.
E. The salt concentration in the airway-surface fluid of people whose lungs produce lowerthan-
average amounts of the antibiotic is generally much lower than that typical of healthy
lungs.

1 Answer

PHoddle
0
High Salt --* Ineffective . This was the hypothesis. But is it really the cause?
C- bridges the gap saying when salt lvl is normal --* effective.
answered Jun 26, 2016 by Beginner (1 point)
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