TOEFL Listening: TPO-TOEFL阅读TPO - F2W892Z0UKNU94X2N$

According to paragraph 4, all of the following are true about metabolites secreted by phytoplankton EXCEPT A. They have a less significant effect on the dominant species of phytoplankton than they do other species of phytoplankton. B. They affects the growth of phytoplankton living in seawater. C. They are secreted in small amounts by individual phytoplankton. D. They cause changes in seawater that result in species succession of phytoplankton.