TOEFL Listening: ETS-TOEFL听力机经 - OD1ZHK5Z3JH39EIRP$

According to the professor, what is the major significance of the Younger Dryas Boundary? A. It provides proof of a sudden climate change. B. It lines the inside of a 13,000-year-old impact carter. C. It contains valuable information on about the composition of meteors. D. It marks the disappearance of large mammal species.