Which of the Following Would Provide Evidence for Reinforcement

Which of the following would provide evidence for reinforcement?

A) Pre-mating isolation between two species is higher in areas where they are sympatric than in areas where they are allopatric; postzygotic isolation is strong in all crosses.
B) Postzygotic isolation between two species is higher in areas where they are sympatric than in areas where they are allopatric; pre-mating isolation is the same in allopatric and sympatric populations.
C) Pre-mating isolation between two species is higher in sympatry than in allopatry; there is no postzygotic isolation in any cross.
D) a and c