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.

A. The pipeline’s construction will disturb sediments at the bottom of the lake, dispersing into the water toxic pollutants that have settled there.

Complete Question: 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' 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, those fears are groundless.

Explanation: The conclusion that the the planned construction will not lead to pollution is based on the assumption that the new technology which prevents leakages. But if there are other factors which will lead to pollution, this weakens the argument.

Option A introduces such a factor. Although the new technology prevents the pipe from leaking, the structure of the pipe in itself will disperse toxic pollutants into the water, pollute Lake Konfa, and reduce the fish population.

Other options

The drainage pattern (Option B) is not related to the construction. Option C strengthens the argument, Option D talks about the effects of leakages, which again does not have any relation to the argument about this specific pipeline construction. Option E talks about the fish population in Lake Konfa but is unrelated to the planned construction.