TOEFL Listening: ETS-TOEFL听力机经 - 8Y48SZ431LKNLB3MP$

Why does the professor discuss maize? A. To point out that phytolith analysis has proven howwidespread its cultivation actually was B. To provide an example of a plant whose phytoliths are unique C. To emphasize the surprising number of subspecies that were suitable for domestication D. To show that phytolith analysis can reveal the timing of a plant's domestication