TOEFL Listening: TPO-TOEFL阅读TPO - P498KQXR26V6VRZRN$

What is the author's primary purpose in paragraph 7? A. To illustrate the importance of studying the brain B. To demonstrate that human beings are the only mammal to desire fine control of movement C. To contrast the functions of the two hemispheres of the brain D. To demonstrate that right-hand preference has existed for a long time