Critical Reasoning

Early in the twentieth century, Lake Konfa became very polluted.
Recently fish populations have recovered as release of industrial pollutants has declined and the lake's waters have become cleaner.
Fears are now being voiced that the planned construction of an oil pipeline across the lake's bottom might revive pollution and cause the fish population to decline again.
However, a technology for preventing leaks is being installed.
Therefore, provided this technology is effective, the fears are groundless.
Which of the following, if true, most seriously weakens the argument?
A. The pipeline's construction will disturb sediments at the bottom of the lake, dispersing into the water toxic pollutants that have settled there.
B. Changes in land use and drainage patterns around the lake mean that the lake's waters are increasingly likely to be affected by agricultural runoff.
C. The leak-preventing technology has been in use for several years without any pipeline in which it is installed developing serious leaks.
D. A major leak of oil from the pipeline would harm not only the lake's fish but also populations of other aquatic animals and plants.
E. Since the beginning of the twentieth century, non-native species of fish have been introduced into the lake and now make up a considerable proportion of its overall fish population

OA is

A

Source: GMATPrep

Experts, pl explain the above.

Yes the answer should be A because though technology is effective and leakage will not happen but the pollutants that have settled will definitely be disturbed and gain the lake will get polluted.

I wish to comment on this problem
B is wrong because of "likely". B is wrong because the weakening action has not happened actually. The weakening action must happen actually though it is only to increase the doubt in an assumption and so in the conclution

Many question in testpre in which correct answer is showned that the weakening action possiblly happen. This is wrong. sorry, I do not remember. next time, I meet a question with this problem I will turn to this post again.

Interesting. It took me a while to find this Question with this set of Answers. There is another question out there with the same question but different answers.

I agree, A. Even though the technology is effective and the fears are groundless (according to the author) the fact that the process of constructing the pipeline will disperse the toxic pollutants in the settlement is cause for fear and will be devastating to the ecosystem.

Hi,
Can someone explain me why did we remove C option?
Thanks in Advance.

Let us identify the premises and the conclusion in this argument.

Premise 1: There are fears that the construction of the pipeline across Lake Konfa's bottom would revive the pollution levels in the lake, resulting in a decline in the fish population
Premise 2: Technology for preventing leaks is being installed

Conclusion: Provided that the technology for preventing leaks is effective, the construction of the pipeline would not result in an increased pollution level and decreased fish population

In CR questions, it always helps to spend a bit of time to think about the author's assumption. The best way to visualize assumptions is to think of them as the things/missing variables which the author assumes to be true in his own mind when going from the premise to the conclusion.

In this case, a crucial assumption made by the author is that "Leakage from the pipeline is the ONLY way via which the pollution levels in the lake would increase and the fish population will decline". But what if there are other ways in which the pipeline construction can increase pollution levels and destroy the fish population? If there are other ways aside from a pipeline leakage that could be detrimental to the fish population, then the future technology would be rendered useless. Since we have to weaken the argument, we are looking for such an answer.

Option A - Correct : This option close matches our lines of pre-thinking above and provides a way aside from pipeline leakage via which the pollution levels can increase (and hence the fish population can decrease). This is a very strong contender.
Option B - Incorrect : Irrelevant - This option doesn't address the pipeline nor the technology being put in place
Option C - Incorrect : This is the exact opposite to what we are looking for since this option says that the technology will be useful in preventing leaks
Option D - Incorrect : Irrelevant - This is a good bit of info to know regarding the seriousness of the issue at hand, but it doesn't answer our question of whether the pollution levels would increase as a result of the pipeline construction
Option B - Incorrect : Irrelevant and Out of Scope

Hence, Option A is our best answer to weaken the above argument.

Please let me know in case anything doesn't make sense.