Answer:
D. Fruit flies prefer mates adapted to the same food source.
Step-by-step explanation:
Food and diet varies depending on the location of an animal, that being said, it is in the nature of an animal to mate with another in order to produce offspring who can survive on the same food source. Instinctively, a fly would see a mate who's diet differed and think that their offspring would not be able to survive due to the lack of that varying food source.