Artificial seaweed made of plastic has been placed on a section of coast in order to reverse beach erosion. The inventor of the seaweed has concluded that the recent buildup of sand on that section of coast proves that the artificial seaweed reverses beach erosion.

Which of the following, if true, would most seriously weaken the inventor's conc1usion?

(A) The amount of recent sand buildup on that section of coast was less than had been predicted on the basis of the results obtained in controlled experiments.
(B) Because artificial seaweed would be buried eventually by additional sand deposits on the coast, more artificial seaweed would need to be put in place every four years.
(C) Artificial seaweed of another material which had been previously developed by the inventor failed to add sand to coastline in past trials.
(D) The amount of recent sand buildup on that section of coast is the same as the amount of recent sand buildup on otherwise very similar sections of coast without artificial seaweed.
(E) The amount of recent sand buildup on that section of coast, although considerable, is not yet enough to replace the amount lost during storms on that section of coast in the last twenty years.