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Since 1985, pollution levels in Lake Thomas have dropped [#permalink]
 25 Sep 2003, 17:46
Question Stats:
22% (02:36) correct
77% (01:15) wrong based on 0 sessions
Since 1985, pollution levels in Lake Thomas have dropped considerably, primarily because of a state program to clean the lake water by means of a water refinery. Ironically, during this same period, the once-abundant population of sunfish in the lake has dwindled.
Which of the following, if true, would best explain why the sunfish population of Lake Thomas has dwindled at the same time that the lake water has become cleaner?
The life spans of sunfish are not diminished by high pollution levels, but the number of offspring they create during their lifetime is diminished.
Several artificial chemicals are introduced into the lake as a result of the refinement process, but these chemicals are known to have a benign effect on fish.
The water refinement process creates an environment extremely favorable to pike, a predator fish.
The heaviest concentrations of sunfish population in the lake are at its northern and northeastern shores, many miles away from the water refinery.
Ever since 1972, a strictly enforced state regulation has prevented anglers from over-fishing Lake Thomas.
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I vote for A. The refinement has nothing to do with dwindling the sunfish population. It is previous pollutants that prevent the sunfish from breeding, and the effect of pollution simply concides with the time of refinement.
C is temptive, but we do not know for sure whether the pike preys on the sunfish. In fact, the reverse situation is possible.
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stolyar it cant be A as the population has dwindled only since the new process was put in place... so C has to be right ...
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on second thots A is right stoylar.. I reread it... as the offsprings havre reduced and the most of the fish would have died in this span. so very few remain.
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C has to be right assuming that the pike preys on the sunfish. But is this assumption valid? I think not.
The right C should be: The water refinement process creates an environment extremely favorable to the pike, a predator fish praying on the sunfish.
As for A: the sunfish population was abundant but did not have enough offsprings. The old fish start to die; the number of the young fish is small, and even clean water cannot correct the situation.
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A small catch here mate.. what if the average fish lives for a span exceeding the period ; )then all must be alive.. so the fish dying is also an assumption ; )
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I thought about it. The CR sections requires that we take the best answer. I hope A is the best, simply the best, as Tina Turner sings. Let's wait for the official answer.
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Re: CR : Pollution [#permalink]
26 Sep 2003, 01:35
praetorian123 wrote: Simple one, but got it wrong!
Since 1985, pollution levels in Lake Thomas have dropped considerably, primarily because of a state program to clean the lake water by means of a water refinery. Ironically, during this same period, the once-abundant population of sunfish in the lake has dwindled.
Which of the following, if true, would best explain why the sunfish population of Lake Thomas has dwindled at the same time that the lake water has become cleaner?
The life spans of sunfish are not diminished by high pollution levels, but the number of offspring they create during their lifetime is diminished.
Several artificial chemicals are introduced into the lake as a result of the refinement process, but these chemicals are known to have a benign effect on fish.
The water refinement process creates an environment extremely favorable to pike, a predator fish.
The heaviest concentrations of sunfish population in the lake are at its northern and northeastern shores, many miles away from the water refinery.
Ever since 1972, a strictly enforced state regulation has prevented anglers from over-fishing Lake Thomas.
My choice is definitely C.
Remember, we are trying to explain the decrease in Sunfish...
(A) states that number of offspring is DIMINISHED by pollution. Hence, if we REDUCE pollution, offspring will no longer be diminished. This certainly does not explain the decrease in Sunfish -- more likely it inplies that an eventually increase will occur.
(B) states that the chemical do not harm fish. Hence, this does not explain the decrease in Sunfish.
(C) states that a predatory fish thrives in the environment created by the refinery. Nitpicking aside, since the subject of the argument is the "sunfish", it is reasonable to assume that the term "predatory" refers to the relationship of the pike to the sunfish. This would certanly explain a decrease in sunfish and IMO is the best choice.
(D). states that the heaviest concentration of pike are far away from the refinery. While this is consistent with (C), it does not in itself explain an overall decrease in the sunfish population.
(E) does nothing to explain the decrease in Sunfish since 1985 and is irrelavent. In fact, it removes a possible explaination for the decrease.
_________________
Best,
AkamaiBrah
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993
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My vote: C
agree with akamaibrah...
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Re: CR : Pollution [#permalink]
26 Sep 2003, 10:38
AkamaiBrah wrote: praetorian123 wrote: Simple one, but got it wrong!
Since 1985, pollution levels in Lake Thomas have dropped considerably, primarily because of a state program to clean the lake water by means of a water refinery. Ironically, during this same period, the once-abundant population of sunfish in the lake has dwindled.
Which of the following, if true, would best explain why the sunfish population of Lake Thomas has dwindled at the same time that the lake water has become cleaner?
The life spans of sunfish are not diminished by high pollution levels, but the number of offspring they create during their lifetime is diminished.
Several artificial chemicals are introduced into the lake as a result of the refinement process, but these chemicals are known to have a benign effect on fish.
The water refinement process creates an environment extremely favorable to pike, a predator fish.
The heaviest concentrations of sunfish population in the lake are at its northern and northeastern shores, many miles away from the water refinery.
Ever since 1972, a strictly enforced state regulation has prevented anglers from over-fishing Lake Thomas. My choice is definitely C. Remember, we are trying to explain the decrease in Sunfish... (A) states that number of offspring is DIMINISHED by pollution. Hence, if we REDUCE pollution, offspring will no longer be diminished. This certainly does not explain the decrease in Sunfish -- more likely it inplies that an eventually increase will occur. (B) states that the chemical do not harm fish. Hence, this does not explain the decrease in Sunfish. (C) states that a predatory fish thrives in the environment created by the refinery. Nitpicking aside, since the subject of the argument is the "sunfish", it is reasonable to assume that the term "predatory" refers to the relationship of the pike to the sunfish. This would certanly explain a decrease in sunfish and IMO is the best choice. (D). states that the heaviest concentration of pike are far away from the refinery. While this is consistent with (C), it does not in itself explain an overall decrease in the sunfish population. (E) does nothing to explain the decrease in Sunfish since 1985 and is irrelavent. In fact, it removes a possible explaination for the decrease. C is the correct answer
Thanks all for a good discussion
Praetorian
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I have an objection, but so be it.
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stolyar wrote: I have an objection, but so be it.
Stolyar, i totally understand the objection about C.
I picked A too,but Akamai's explanation makes sense....the pollution
levels are down, so there should not be any problems with the creation of
offspring. A doesnt help us get there...
I agree that C is way too general. but its the BEST ANSWER.
Thanks All
Praetorian
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