[单项选择] Genetic engineering holds great potential payoffs for farmers and consumers by making crops resistant to pests, diseases, and even chemicals used to kill surrounding weeds. But new research raises concerns that altering crops to withstand such threats may pose new risks from none other than the weeds themselves. This is due to the weeds ability to acquire genes from the neighboring agricultural crops. Researchers found that when a weed cross-breeds with a farm-cultivated relative and thus acquires new genetic traits possibly including artificial genes engineered to make the crop hardier the hybrid weed can pass along those traits to future generations. "The result may be very hardy, hard-to-kill weeds," said Allison Snow, a plant ecologist at Ohio State University in Columbus who conducted the experiments over the past six years along with two colleagues. They presented their results last week at the annual meeting of the Ecological Society of America in Madison, Wisconsin.
A. the results of recent research
B. dangers inherent in the nature of weeds
C. risks of altering crops’’ genetic make-ups
D. threats posed by chemicals used to kill weeds

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