TOEFL Listening: TPO-TOEFL听力TPO - 1FTOL4G93C777X2VR$

What does the professor mainly discuss? A. The importance of zooplankton in the marine food chain B. The interdependence of two types of tiny marine organisms C. A physical feature of zooplankton that makes them well adapted for swimming D. A phenomenon observed in some species of zooplankton