For example, corn and cotton that are resistant to pests in the United States may accelerate the emergence of some more difficult pests. All molecules of this crop secrete a small amount of "insecticides", a pesticide like any pesticide It is also possible to choose "aerosols" that kill certain pests. What's the right thing to understand? ['The emergence of new pests is related to the pollution of the "aerosol" secreted by insect-resistant crops.', "U. S. genetic maize and cotton varieties can't deal with pests.", 'Insect-resistant corn and cotton may promote the emergence of pests that are more difficult to kill.', 'The crop that can resist insect pests, while resisting pests, it also protects some pests.']