In the last few years, plant scientists have been able to genetically engineer seeds to produce crops highly resistant to insect damage. Farmers growing crops with these seeds will be able to spend significantly less on pesticides. This cost reduction would more than make up for the higher cost of the genetically engineered seeds. Clearly, therefore, farmers who grow crops from genetically engineered seeds will be able to reduce their costs by using them.

Which of the following, if true, most weakens the argument?

A. Plant scientists have not yet developed insect-resistant strains of every crop that is currently grown commercially.
B. The cost of several commonly used pesticides is expected to rise in the next few years.
C. Crops grown from the genetically engineered seeds require significantly more fertilizer and water to grow well than do crops grown from nonengineered seeds.
D. In the future, the cost of genetically engineered seeds is likely to fall to the level of nonengineered seeds.
E. The crops that now require the greatest expenditure on pesticides are not the ones for which genetically engineered seeds will become available.

C