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Sunflowers growing in pots were placed, with their roots submerged, in the pond contaminated with radioactive elements. The sunflowers kept growing; in the process, they absorbed radioactive elements. Within twelve days, 85 percent of the radioactive elements were removed from the water, which is no less than can be accomplished with the much more expensive conventional filtration techniques. Scientists, therefore, propose using sunflowers for decontamination wherever there are radioactively contaminated ponds.

Which of the following, if true, points to a limitation on the applicability of the proposed method of decontamination?


Option A:

Some plants other than sunflowers can also remove radioactive elements from water.

Option B:

The water in many ponds contaminated with radioactive elements is so cold that it would kill sunflowers whose roots were submerged in it.

Option C:

Sunflowers that grow with their roots submerged in water grow less well than sunflowers growing under optimal conditions on dry land.

Option D:

Only species of sunflowers with large leaves can have their roots submerged in water and still keep growing

Option E:

In ponds in which the circulation of the water is artificially increased, sunflowers absorb radioactive elements far faster than they do in other ponds.

Difficulty Level



Option B is the right answer.

Option Analysis

Question type: Flaw

Summary of the argument: The argument makes a plan/proposal. The plan is to use sunflowers to filter the ponds that are radioactively contaminated. The author, therefore, assumes that the plan will work yielding benefit and reduce the harm that the radioactive elements are likely to cause. We are now supposed to find out some option that points a problem with the plan.

A) This doesn’t point out any flaw to the original plan.

B) Correct Answer

C) This doesn’t tell us how well the radioactive elements will be cleared from the pond.

D) If we are able to find such sunflowers then it shouldn’t really be a problem.

E) Again doesn’t point a flaw with the plan proposed in the argument.