TOEFL Reading: ETS-TOEFL阅读机经 - H423EEV2V32TV96RL$

In paragraph 2, what is the author's purpose in mentioning the estimated numbers of birds and coral fish species on various Oceanic islands? A. To give examples of the wide range of species that can be found on Oceanic islands B. To demonstrate how much knowledge about Oceanic species has been accumulated C. To illustrate the decline in species diversity from west to east on Oceanic islands D. To identify the influence of latitude upon Oceanic plants and animals