TOEFL Listening: ETS-TOEFL听力机经 - Q939PLIV9IZ6Z43TP$

The professor discusses the Earth's crust in order to reinforce which of the following ideas? A. Ocean floor spreading is still debated among modern oceanographers. B. Tectonic movement has been occurring throughout history. C. Continental drift commonly leads to widespread volcanic activity. D. That ocean floor spreading is connected to continental movement.