TOEFL Listening: ETS-TOEFL听力机经 - C93Q1I55H6GDWNYTP$

What is the professor's opinion about the classification system she discusses? A. It is flawed to the point of being unusable and should be replaced. B. It is only useful for providing general information about various groups. C. It should be expanded to include other types of groups. D. It is not ideal, but it is more precise than earlier systems of classification.