TOEFL Listening: ETS-TOEFL听力机经 - M_CFO09SWDA3A4X4P$

What is the main topic of the lecture? A. Evidence for the spreading of the ocean floor and movement of continents B. The elements that make up sediments on the ocean floor and their significance C. Arguments and evidence for and against the theory of continental drift D. Features of the seafloor and how their movement impacts the oceans