TOEFL Listening: ETS-TOEFL听力机经 - 723KA91Q57R44IVEP$

Why does the professor mention a cloud of dust? A. To explain how the North Atlantic conveyor belt works. B. To provide evidence for a decrease in temperature at the beginning of the Younger Dryas. C. To emphasize the speed at which climate change can occur. D. To explain how indium deposits worldwide relate to one theory about the Younger Dryas.