It is crucially important to farmers that the herbicides they use to control weeds not damage their crops. One very effective herbicide is safe for corn but lethal to soybeans. To maintain the nutrients in the soil, soybeans and corn are frequently sown in a field in alternate years. Therefore, in such fields, the herbicide can safely be used on the corn, since the two crops are not sown together in the same field.

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

Correct answer marked below

The herbicide has not been shown to harm insects, birds, or other animals that come in contact with it.

Scientists have so far failed in their attempts to breed soybeans that are resistant to the herbicide.

Some of the herbicide persists as a residue in the soil for over a year.

Correct

To be effective, the herbicide must be applied early in the growing season of the corn.

Soybean crops do not require the application of herbicides to the same extent as do corn crops.

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Comments

BalApr 21

C is pretty obvious once you see the residue angle. If it lingers over a year, next season's soybeans are toast.

RadhikaMay 5

yeah the alternate-year thing is the whole trap here. took me a sec to connect it.

What this question tests

Whether you can identify the option that most undermines an argument's conclusion.

Choosing an irrelevant objection or one that attacks the premise rather than the reasoning.