Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists’ hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.
B. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.
E. High salt concentrations have an antibiotic effect in many circumstances.
IMO-B. If C is the right answer, pls explain?
Healthy lungs
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Surely C
Healthy lungs produce a natural antibiotic that protects them from infection by routinely k!II!ng harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists’ hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal -->irrelvant
B. A sample of the antibiotic was capable of k!II!ng bacteria in an environment with an unusually low concentration of salt -->this is a weaken. "unusually low concentration of salt" means an average antibiotic usually demolish k!II!ng bacteria in high ambience concentrating of salt --> this weaken the argument
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria --> best. the argument is "high salt concentration is what makes the antibiotic ineffective" which also means "lower salt concentration can make the antibiotic more effective". Here, "normal" means lower than "high" --> strengthen
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces --> irrelevant
E. High salt concentrations have an antibiotic effect in many circumstances -->weaken
IMO-B. If C is the right answer, pls explain?[/quote]
Healthy lungs produce a natural antibiotic that protects them from infection by routinely k!II!ng harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists’ hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal -->irrelvant
B. A sample of the antibiotic was capable of k!II!ng bacteria in an environment with an unusually low concentration of salt -->this is a weaken. "unusually low concentration of salt" means an average antibiotic usually demolish k!II!ng bacteria in high ambience concentrating of salt --> this weaken the argument
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria --> best. the argument is "high salt concentration is what makes the antibiotic ineffective" which also means "lower salt concentration can make the antibiotic more effective". Here, "normal" means lower than "high" --> strengthen
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces --> irrelevant
E. High salt concentrations have an antibiotic effect in many circumstances -->weaken
IMO-B. If C is the right answer, pls explain?[/quote]
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After eliminating A, D and E, we are left to choose between B and C.
B) The key word to note here is "unusually low" and it means lower than normal which take is actually misleading and goes against the passage.
C)-Clearly states that with a "Normal" salt content, the bacteria is resisted and hence we can conclude that the amount of salt determines the effectiveness of the antobodies.
Hope this helps
B) The key word to note here is "unusually low" and it means lower than normal which take is actually misleading and goes against the passage.
C)-Clearly states that with a "Normal" salt content, the bacteria is resisted and hence we can conclude that the amount of salt determines the effectiveness of the antobodies.
Hope this helps
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C says that tissue can resist bacteria in normal salt solution. It says nothing about high salt concentration of the solution. It says nothing about the antibiotic becoming ineffective. In fact the antibiotic can still remain effective in the salt solution and act alongside salt solution in resisting the effect of bacteria.Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists' hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.
B. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.
E. High salt concentrations have an antibiotic effect in many circumstances.
Experts, please comment.
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The argument concludes that a high salt concentration in people with cystic fibrosis CAUSES their inability to resist bacteria.crackgmat007 wrote:Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists� hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.
B. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.
E. High salt concentrations have an antibiotic effect in many circumstances.
One way to strengthen a causal argument is to show the following:
If the cause is removed, the effect does not happen.
C: When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
Here, the cause is removed (the high salt concentration is replaced with a normal salt concentration), and the effect does not happen (the tissue from people with cystic fibrosis is able to resist bacteria), STRENGTHENING the conclusion that a high salt concentration in people with cystic fibrosis CAUSES their inability to resist bacteria.
The correct answer is C.
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Dear GMATGuruGMATGuruNY wrote:The argument concludes that a high salt concentration in people with cystic fibrosis CAUSES their inability to resist bacteria.crackgmat007 wrote:Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.
Which of the following, if true, most strongly supports the scientists� hypothesis?
A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.
B. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.
C. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
D. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.
E. High salt concentrations have an antibiotic effect in many circumstances.
One way to strengthen a causal argument is to show the following:
If the cause is removed, the effect does not happen.
C: When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.
Here, the cause is removed (the high salt concentration is replaced with a normal salt concentration), and the effect does not happen (the tissue from people with cystic fibrosis is able to resist bacteria), STRENGTHENING the conclusion that a high salt concentration in people with cystic fibrosis CAUSES their inability to resist bacteria.
The correct answer is C.
Why B is wrong? When there is low concentration of slat, the antibiotic kills the bacteria.
Thanks
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In the CR above, the cause = a NORMAL salt concentration (seen in healthy lungs) is replaced with a HIGH salt concentration (seen in people with cystic fibrosis).Mo2men wrote: Dear GMATGuru
Why B is wrong? When there is low concentration of slat, the antibiotic kills the bacteria.
Thanks
B: A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.
This option does not simply remove the cause (leaving a normal salt concentration) but discusses an entirely NEW situation (an UNUSUALLY LOW salt concentration).
Since neither healthy people nor people with cystic fibrosis have an unusually low salt concentration, the information in B is irrelevant.
Eliminate B.
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