TOEFL Reading: ETS-TOEFL阅读机经 - 4_23CFJO5P6EC513L$

In paragraph 2, why does the author discuss the ancestors of vertebrates and arthropods? A. To explain how a single feature can cause the extinction of entire groups of organisms B. To identify some factors that determine how large an organism can become C. To illustrate the point that earlier developments influence the possibilities for future development D. To emphasize the role of the environment in the development of organisms