TOEFL Reading: ETS-TOEFL阅读机经 - Q56XDC27XYQX2NFXL$

According to paragraph 3, which of the following is true of plankton after the extinctions at the end of the Cretaceous A. Diatoms and dinoflagellates suddenly became very rare. B. Single-celled types of plankton were replaced by more complicated microorganisms. C. The plankton found in later deposits are closely related to single-celled Late Cretaceous microorganisms. D. The only types of Late Cretaceous plankton to survive extinction were those protected by cysts.