题目选项分析

Insect infestations in certain cotton-growing regions of the world have caused dramatic increases in the price of cotton on the world market. By contrast, the price of soybeans has long remained stable. Knowing that cotton plants mature quickly, many soybean growers in Ortovia plan to cease growing soybeans and begin raising cotton instead, thereby taking advantage of the high price of cotton to increase their income significantly, at least over the next several years.

Which of the following, if true, most seriously weakens the plan's chances for success?

【选项】Tests of a newly developed, inexpensive pesticide have shown it to be both environmentally safe and effective against the insects that have infested cotton crops.