GWD-2-19

Q19:

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?

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


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


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


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


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

   Answer: ? Thanks

Agree with B.

so, B means that the ponds surveyed and the ponds intended to be applicated are different?

otherwise, B would be incorrect ?

我选的D。

B中说is so cold that it would kill sunflowers whose roots were submerged in it.

但是文中已经说了The sunflowers kept growing

所以如果选B不就是反对前提了吗？？

D是对该措施的可行性提出问题，所以是weaken，不是吗？