TOEFL Listening: ETS-TOEFL听力机经 - XU844UJMBN1F84JPP$

What does the professor imply when she talks about the handicap principle? A. Weak animals defend themselves by increasing the volume of their vocalizations. B. Most animals' vocalization behavior is not explained by the handicap principle. C. Some animal species cannot afford the costs of honest communication. D. Individual animals' behavior is consistent with long-term benefit to the species.