Which of the following is an assumption on which the argument depends? A. Corn is the principal food of stem borers that live on continents other than North America. B. The wasps are capable of surviving in North America long enough to eat significant numbers of stem borers. C. No wasp in North America is closely related to the species of wasp that eats stem borers. D. On continent other than North America, the wasps control stem borers more effectively than does any other pest control measure. E. Corn crops on continents other than North America are not damaged by any insect pests other than stem borers.