There Is No Simple or Universally Accepted Explanation for the Fact

There is no simple or universally accepted explanation for the fact that all cultures ban incest. However, the most accepted explanation for the incest taboo is

A) genetically programmed instinctive horror.
B) a widespread and well-founded fear of biological degeneration.
C) following rules of exogamy is adaptively advantageous.
D) isolated social groups are better at survival.
E) a genetically determined attraction for those most different from us.