TOEFL Listening: TPO-TOEFL听力TPO - 3CF1J2Z1MP85T105R$

What does the professor want the student to do when they write their papers? A. Show a connection between history and another field in which they are interested. B. Develop a research topic that has not been investigated before. C. Explain how an aspect of United States culture has changed over time. D. Describe early difference between regions of the United States.