TOEFL Listening: TPO-TOEFL听力TPO - A2_T12FBE2JA7Z55R$

What does the professor conclude about the results of Derryberry's research? A. They cannot be applied to other species of songbirds. B. They suggest that modern white-crested sparrows are dividing into two species. C. They suggest that behavioral barriers cause speciation faster than physical barriers do. D. They show that old technology can be used in new ways.