Drosophila mojavensis and drosophila arizonae are closely related and reproductive isolation between them is incomplete. they have overlapping distributions in the sonoran desert, although there are also areas where they occur allopatrically. which of the following conditions would be required in order to infer reinforcement? (a) premating isolation is stronger in areas where they are allopatric than in areas where they are sympatric.(b) there is postzygotic isolation in areas where they are sympatric.(c) premating isolation is stronger in areas where they are sympatric than in areas where they are allopatric.(d) b and c are both required.(e) a and b are both required.