TOEFL Listening: ETS-TOEFL听力机经 - 444S38WB55M398Q8P$

Why does the professor mention volumes of literature? A. To point out an advantage of the printing press B. To emphasize the amount of printing Petrucci did C. To explain how Petrucci's prints were packaged and sold D. To make a point about the cost of Petrucci's prints