Which of the following is a possible advantage for the environment of having farmers use plants that genetically produce bt toxin? a) plants with genes for the toxin are eaten less often by insects, and therefore less insecticide is needed. b) plants that produce bt toxin must be grown from new seeds each season, and therefore fewer of them are planted. c) bt toxin is advantageous to many species of invertebrates that grow in the same fields. d) harvesting plants with these genes is less disturbing to the soil layers where they are planted. e) plants with these genes must be sprayed with the organism, but need much less than other plants.