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# Just a few years ago salmon could not survive in the oxygen

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Senior Manager
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Just a few years ago salmon could not survive in the oxygen [#permalink]

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19 Jul 2011, 05:01
Just a few years ago salmon could not survive in the oxygen-starved and polluted Thames. Nor could many other species. But now, after years of determined effort, the salmon have returned, and that is a sure sign that the river is pollution-free.

Each of the following indicates a possible flaw in the reasoning in the passage above EXCEPT:

(A) The salmon that have returned may be of a strain that is unaffected by the pollutants.
(B) The pollution may have been reduced to a level at which the salmon can survive.
(C) Oxygen starvation is often a consequence of pollution, and this may have killed the salmon.
(D) The salmon may have been killed by one particular pollutant, which has now been removed while others remain.
(E) There may still be pollution, but its nature may have changed to a form that salmon can tolerate.

None of the answer choice made sense to me..pls help me understand the reasoning behind every answer...
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19 Jul 2011, 06:22
DeeptiM wrote:
Just a few years ago salmon could not survive in the oxygen-starved and polluted Thames. Nor could many other species. But now, after years of determined effort, the salmon have returned, and that is a sure sign that the river is pollution-free.

Each of the following indicates a possible flaw in the reasoning in the passage above EXCEPT:

Argument: Pollution is removed completely; 100%

(A) The salmon that have returned may be of a strain that is unaffected by the pollutants.
Pollution exists; Salmon is of different type.

(B) The pollution may have been reduced to a level at which the salmon can survive.
Pollution NOT completely removed maybe 80% but NOT 100%.

(C) Oxygen starvation is often a consequence of pollution, and this may have killed the salmon.
This is giving us a cause why Salmons died; it is not telling us anything about the present state of the river, neither is it telling us about the salmons that returned.
In a way this fact strengthens the reasoning that now there is abundant oxygen because of 0 pollution and thus Salmon survive.

(D) The salmon may have been killed by one particular pollutant, which has now been removed while others remain.
Out of 100 pollutants; 1 killer pollutant gone and Salmons are back. This doesn't make river pollution free.

(E) There may still be pollution, but its nature may have changed to a form that salmon can tolerate.
Pollution still there but in a different form

None of the answer choice made sense to me..pls help me understand the reasoning behind every answer...

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19 Jul 2011, 06:49
DeeptiM wrote:
Just a few years ago salmon could not survive in the oxygen-starved and polluted Thames. Nor could many other species. But now, after years of determined effort, the salmon have returned, and that is a sure sign that the river is pollution-free.

Each of the following indicates a possible flaw in the reasoning in the passage above EXCEPT:

Argument: River is Pollution Free.

(A) The salmon that have returned may be of a strain that is unaffected by the pollutants.
Pollution Still exists, so indicates a flaw.

(B) The pollution may have been reduced to a level at which the salmon can survive.
Pollution reduced but Still exists, so indicates a flaw.

(C) Oxygen starvation is often a consequence of pollution, and this may have killed the salmon.
Doesn't say anything w.r.t to Pollution presently in river. Hence not indication any flaw. Logical opposite!!

(D) The salmon may have been killed by one particular pollutant, which has now been removed while others remain.
One pollutant removed but Pollution Still exists, so indicates a flaw.

(E) There may still be pollution, but its nature may have changed to a form that salmon can tolerate.
Pollution Still exists in a different form, so indicates a flaw.

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Cheers,
Varun

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19 Jul 2011, 07:01
Clear C
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19 Jul 2011, 07:46
OA is C...thanks guys!!
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19 Jul 2011, 10:55
+1 C
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19 Jul 2011, 19:33
C for me as well.

Crick
Re: CR - Salmon   [#permalink] 19 Jul 2011, 19:33
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