TOEFL Reading: ETS-TOEFL阅读机经 - 76CQ255S1406I_6TL$

In paragraph 4, why does the author include the quotation by Carl Sagan A. To explain the connection between dinosaur extinction and the extinction of other animal species B. To support the claim about species extinction being due to indirect causes and effects C. To show that scientists have revised their ideas greatly in the last thirty years D. To identify the differences between the various theories for the extinction of dinosaurs