TOEFL Listening: ETS-TOEFL听力机经 - INI93Z51X8SSK18IP$

What is the main purpose of the lecture? A. To compare two types of chimpanzee grooming behaviors. B. To explain the role of the alpha male in chimpanzee communities. C. To discuss the relationship between grooming behavior and dominance in chimpanzees. D. To challenge the belief that alpha male chimpanzees groom each other.