TOEFL Listening: ETS-TOEFL听力机经 - UQI11DY6NUT54YO6P$

Why does the professor say this : A. To emphasize that the air quality in the Utah desert is very good. B. To show that the student has pointed out an important fact. C. To remind the student that she already covered the topic. D. To indicate that the student has made an incorrect assumption.