TOEFL Listening: ETS-TOEFL听力机经 - PTGVRH8HE8RBA2Z9P$

Why does the professor mention an artistic digital photography? A. To emphasize the impact of digital photography on modern painting. B. To point out that the cost of making photographs has gone done. C. To indicate the ease with which photographs can be altered. D. To explain the increase in the number of documentary photographs.