TOEFL Listening: TPO-TOEFL阅读TPO - 514D3ZN3EQTDH8Z1N$

Why does the author mention "soldiers yawning before combat, musicians yawning before performing, and athletes yawning before competing"? A. To argue that just the expectation of physical activity can make some people feel tired B. To explain how the view that people yawn because they are tired accounts for yawning before stressful situations C. To support the view that yawning helps prepare a person for mental or physical exertion D. To provide anecdotal evidence that conflicts with the experience of the volunteers in the study