Theoretically, the production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) should
A) result in the extinction of one of the two parental species.
B) cause convergent evolution.
C) strengthen postzygotic barriers between horses and donkeys.
D) weaken the intrinsic reproductive barriers between horses and donkeys.
E) eventually result in the formation of a single species from the two parental species.
Answer: C