when horses and donkeys mate, their offspring are mules. mules are sterile because they cannot produce functional gametes. this is evidence that: (select the best answer)group of answer choiceshorses and donkeys are separated by a prezygotic barrier.horses and donkeys are separated by genetic drift.horses and donkeys are members of the same species.horses and donkeys are separated by a postzygotic barrier.horses and donkeys are separated by a founder event.flag question: question 2