We are told that a subset of fruit flies called the picture winged drosophilids is represented in Hawaii by 106 species. We also know that all of the fruit fly species in Hawaii are thought to be descendants of the same one or two ancestral females.
So, if it is a fruit fly species in Hawaii, then it's thought that these flies are the descendants of the same one or two ancestral female fruit flies.
FFH ==> D1-2FFF not D1-2FFF ==> not FFH
Answer choice (A) states: "All of the picture winged drosophilids in Hawaii are believed to be the descendants of the same one or two ancestral female fruit flies."
So, since we know that picture winged drosophilids are a type of fruit fly, it's clear that "all of the picture winged drosophilids IN HAWAII" fall under the category of "fruit fly species in Hawaii."
Thus, we can validly infer, since the picture winged drosophilids in Hawaii are a fruit fly species in Hawaii, that it's believed that these flies are the descendants of the same one or two ancestral female fruit flies, i.e. answer choice (A).
Hope that was helpful! Please let us know if you have any other questions.
