According to the graph attached to support the task, I think that I recognized the correct answer, and I bet one negative consequence of using an insecticide is that it selects for insecticide-resistant organisms. Actually, this option is the most impactful for environment, as the rest of the options pose as advantages. (besides the last one, but it does not make sense as the iformation doe not coincide with graph)
I hope you will agree with me.