TOEFL Listening: ETS-TOEFL听力机经 - J9N5RBRW5CV1351SP$

According to the professor, what did researchers conclude after analyzing the recordings of crying newborns? A. The amount of air in the lungs determines the pitch of a newborn's cry. B. Most newborns cry with rising intonation. C. A newborn can control the pitch and volume of its cries. D. The loudness of a newborn's cry is related to whether or not the mother can hear it.