Biologists have noted reproductive abnormalities in fish that are imme

Question

Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills. One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish. However, dioxin is unlikely to be the cause, since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.

Which one of the following statements, if true, most seriously weakens the argument?

Which one of the following statements, if true, most seriously weakens the argument?

(A) Some of the studies that show that fish recover quickly during shutdowns were funded by paper manufacturers.

(B) The rate at which dioxin decomposes varies depending on the conditions to which it is exposed.

(C) Normal river currents carry the dioxin present in the river far downstream in a few hours.

(D) Some of the fish did not recover rapidly from the physiological changes that were induced by the changes in hormone concentrations.

(E) The connection between hormone concentrations and reproductive abnormalities is not thoroughly understood.

vjsharma25 · Accepted Answer

The argument is saying that dioxin can not be the cause for fish problem.Since dioxin doesn't decompose very easily it must be present in the water even when the mill is shutdown.But strangely fish recover.So there is some other cause to the fish problem.
So any answer choice which can show that indeed dioxin is the cause of the problem, is the right answer.

"C" says that Normal river currents quickly carry the dioxin far downstream.It means that dioxin is washed away from the fish area,thats why they recover.During normal operation of the mill,there is continuous release of dioxin in the river,thats why normal current can't carry the substantial amount of dioxin with it.So it proves that dioxin is the cause.Hence the answer.

KarishmaB · Answer

Context: 
We are talking about the fish immediately downstream of a paper mill. They are facing reproductive issues. 
Possible Cause - Dioxin which mills release every day. It alters fish hormones

Premises: 
Fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns 
Dioxin decomposes very slowly in the environment.

The author is saying that when the mill shutdown for a few days (no new dioxin coming in the water) and old dioxin is still present (because it decomposes very slowly in the environment - in the water), fish recover normal hormone concentrations. It means that something else might be responsible for the physical issues the fish are facing because even with the dioxin present (because it decomposes very slowly), the fish regain the normal balance. It means the mills might be releasing some other chemical affecting the fish or something else may be responsible.

Conclusion: 
Dioxin is unlikely to be the cause of reproductive issues.

We have to weaken the conclusion.

(A) Some of the studies that show that fish recover quickly during shutdowns were funded by paper manufacturers.

'Some' studies were funded by paper manufacturers, not all. Perhaps some were independent? We can't say. Not enough info.

(B) The rate at which dioxin decomposes varies depending on the conditions to which it is exposed.

We know that dioxin decomposes very slowly in the environment. The rate of decomposition could vary say 1 unit per million per day or 2 units per million per day or 5 units per million per day depending on say water temperature etc but the rate will be very low. So the old dioxin should be present in the water when the mill is shut down and hence it should affect the fish. It doesn't weaken our argument.

Saupayan  - We are talking about the rate at which dioxin decomposes in the environment. When it is taken in by the fish, how it impacts the fish and what chemicals it converts into etc is irrelevant. We know that it causes hormonal imbalance when it goes inside the fish and that is all. The rate of decomposition is related to the rate at which it breaks down while present in the water. 
The question is fine and could very well be an official question.

(C) Normal river currents carry the dioxin present in the river far downstream in a few hours.

This tells us that the old dioxin does not stay in the water because it is carried far away by the river. Then it is possible that the dioxin is the one affecting the fish. The reason the fish recover when the mills shut down for a few days is that no new dioxin is coming into the water. 
Correct.

(D) Some of the fish did not recover rapidly from the physiological changes that were induced by the changes in hormone concentrations.
 
It says 'some' while we are talking about the fish in general. Because some did not recover rapidly, we cannot say that dioxin may have been responsible.

(E) The connection between hormone concentrations and reproductive abnormalities is not thoroughly understood.
 
It doesn't give us any meaningful information.

Answer (C)

diebeatsthegmat · Answer

finally, i now understand the CR.... 
the main point is that the CR supposed that saying the eproductive abnormalities in fish caused by dioxin from paper mill, the dioxin which is released daily far downstream is totally wrong because the dioxin decomposes very slowly in ENVIROMENT and since the paper mill shutdowns sometimes and the fact is that the fish recovered very quickly right after the paper mill shutdowns ( shutdowns here is it stop releasing dioxin in the river and when it stop releasing dioxin in the river, the fish becomes nornal again, like nothing happen)

C weakens it by saying that although paper mills stop releasing dioxin into the river sometimes but its effect is still there because the river carrys dioxin in hours....

does it help?

this CR is tough... is it from Lsat?

heygirl · Answer

Conclusion here is dioxin is not the cause

(A) Some of the studies that show that fish recover
quickly during shutdowns were funded by
paper manufacturers. not related to conclusion 
(B) The rate at which dioxin decomposes varies
depending on the conditions to which it is
exposed. if anything,strengthens the argument 
(C) Normal river currents carry the dioxin present in
the river far downstream in a few hours. best answer. it says that dioxin travels far downstream because of the currents. Hence, the first statement of the argument is weakened and thus the conclusion. 
(D) Some of the fish did not recover rapidly from
the physiological changes that were induced by
the changes in hormone concentrations. unrelated to argument 
(E) The connection between hormone concentrations
and reproductive abnormalities is not
thoroughly understood.  again,unrelated

nikhilsrl · Answer

I did not quite understand your analysis. You are saying that "Normal river currents quickly carry the dioxin far downstream.It means that dioxin is washed away from the fish area,thats why they recover". If so this is strengthening the argument isn't it? From this how did you deduce that "During normal operation of the mill,there is continuous release of dioxin in the river,thats why normal current can't carry the substantial amount of dioxin with it". Anyways as per the argument fish recover when the mill is shutdown. So the current has time to take the dioxin further downstream.

vjsharma25 · Answer

runitback · Answer

The argument given against dioxin is as follows:

Fact - Dioxin decomposes very slowly in the environment
Fact - Fish recover normal hormone concentrations quickly during mill shutdowns (presumably while dioxin is not being released into the environment)
Conclusion - Dioxin is unlikely to be the cause (of hormone imbalance in fish)

However, if normal river currents carry the dioxin present in the river far downstream in a few hours, then it doesn't matter that that dioxin decomposes slowly - it has all been carried away downstream, which means that the fish are now in dioxin-free conditions. Therefore, the fact that the fish recover quickly can't be used to rule out dioxin as the original cause of altered hormone concentrations.

arvind910619 · Answer

Wow what a question .
The answer has to be C.
It is mentioned in the passage that Dioxin decomposes very slowly.
And if the water carry Dioxin very far in the river then the fish there will be affected .
So C is the answer .
I would also like an analysis of Option A please .
Thanks in advance

Kritisood · Answer

Could someone please explain why answer choice B is incorrect? if the rate at which dioxins decompose vary depending on conditions its exposed to, then if the dioxins are exposed to different conditions in the paper mills factory it would explain why they actually decompose faster when the mills shut down.

Kritisood · Answer

Could someone please explain why answer choice B is incorrect? if the rate at which dioxins decompose vary depending on conditions its exposed to, then if the dioxins are exposed to different conditions in the paper mills factory it would explain why they actually decompose faster when the mills shut down.

nightblade354   GMATNinja   daagh   egmat

nightblade354 · Answer

Kritisood , think about (B) for a minute. What conditions are they talking about? Any assumption you make to strengthen the argument can be made to weaken the argument as well. You say that because they are exposed, therefore they decompose faster. Well, what if the factors made the toxin last longer and decompose slower? We are only told that there is an impact; we are not told the relationship.

CrackverbalGMAT · Answer

Hi Kriti

Option B states that dioxins decompose at different rates depending on the conditions to which it is exposed. However, while this could be a comparison between the rates of decomposition, it says nothing about the  absolute  rate of decomposition.

Secondly, the stimulus in the question very clearly states that dioxin decomposes very slowly in the environment. Any facts presented in the question stimulus are to be accepted at face value. Combining the two (the question stimulus + option B), we can surmise that even though the the rate of decomposition of dioxins in the environment may vary, all of those rates would still be very slow. Thus, the reasoning presented in the stimulus still holds - the slow rate of decomposition added to the quick recovery of hormone concentrations by the fish even during brief shutdowns makes it unlikely that dioxins are the cause. Hence option (B) does not weaken the argument.

Hope this helps.

aniket16c · Answer

Thank you  vjsharma25  for posting this brilliant question:

Argument - Reproductive abnormalities are because of dioxin. Dioxin is released daily. Dioxin affects the hormones. (Assumption that hormones affect the reproductive capability of the fish). 
Conclusion - Dioxins do not affect. Reason - Fish recover the hormones during shut downs

Weakener idea - Dioxins do affect the fish and they recover the hormones because of some other reason.

(A) Some of the studies that show that fish recover quickly during shutdowns were funded by paper manufacturers.
- Some can include (1 to 90%). If some = 1% of the studies then this statement cannot weaken the conclusion
-Wrong

(B) The rate at which dioxin decomposes varies depending on the conditions to which it is exposed.
- Varies is really a vague term. Varies can mean the rate either is higher or is lower than provided. 
- Wrong

(C) Normal river currents carry the dioxin present in the river far downstream in a few hours.
- Normal river currents - current not affected by the dioxin deposition = when the factories are temporarily off. If normal currents carry the dioxin away, the dioxin is not present when it was observed that fish recovered their hormones. This means that when the dioxin is present the hormones are affected. 
This causation suggests that dioxin thus affect the hormones.
- Correct

(D) Some of the fish did not recover rapidly from the physiological changes that were induced by the changes in hormone concentrations.
Similar to choice A, some can include anything from 1% to 99%.
- Wrong

(E) The connection between hormone concentrations and reproductive abnormalities is not thoroughly understood.
- I selected this option during my first attempt. However, this option is not similar to use of "some". We do not require to know the exact reason why or how the hormones affect reproductive system. This option could have been a contender if it was stated that the connection is doubtful. 
- Wrong

kagrawal16 · Answer

IMO,

Dioxin does not hurt the fish
why ?
- fish recover fast "although" during occasional shutdowns
and
- it decomposes slowly.

The author admits that the recovery is seen ALTHOUGH during occasional shutdowns 
BUT he also believes that the cause that is the dioxin is still present because dioxins degrade into the environment slowly. Slow degradation means that the dioxins do not become ineffective overnight when the mills are shut.

Point: Therefore although dioxins are present but the mills are admittedly shut, the fish can recover.

Choice C says that the dioxins are washed away and hence not present. (No cause thats why you see no effect).

jim441 · Answer

Pls help. Unable to understand.

Saupayan · Answer

GMATNinja   GMATNinja Two  KarishmaB 
I really need your expert advise on this question. First of all, is this really an official question?
Coming to the question itself, I understand why option D is correct. However, I contend option B is also correct (based on how you interpret it - hence my first question, is it even official because official shouldn't have such possible ambiguity)

Here's why I think option B is correct (as a side note, this was my first impulse when I read it and I still can't shake it off):

Which one of the following statements, if true, most seriously weakens the argument?

(B) The rate at which dioxin decomposes varies depending on the conditions to which it is exposed.

So basically the author is saying, hey dioxin can't be the cause because dioxin decomposes very slowly in the environment. However, he isn't saying what dioxin does inside the body of a fish. Maybe it decomposes quickly inside a fish (this is exactly what option B is saying - condition in this case being inside fish body). 
So, the author is assuming, hey dioxin takes a long time to decompose, but fish recover quickly when no new dioxin is released (i.e. factory shut). This means dioxin isn't causing the problem.
What if the actual explanation is something like: hey fish are affected by the dioxin entering their body and inside their body, the dioxin decomposes quickly? you would notice this effect hand the factories not being releasing a continuous stream of dioxin. So, the only time you see this effect is when the factories are actually shut for a prolonged period.

What am I missing here?

VerbalBot · Answer

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Biologists have noted reproductive abnormalities in fish that are imme

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Biologists have noted reproductive abnormalities in fish that are imme

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