TOEFL Listening: TPO-TOEFL阅读TPO - 503G01A594I2Q1C2N$

Paragraph 3 supports which of the following statements about the developmental theory of yawning? A. The theory is attractive because it explains yawning from the perspective of Darwinian evolution B. The theory is unsatisfactory because it cannot explain the lung deformities of infants C. The theory is questionable because it does not explain why a useless and inconvenient behavior would continue into adulthood D. The theory is incomplete because it does not explain all the evolutionary stages in the development of yawning