TOEFL Listening: ETS-TOEFL听力机经 - 9YBAB2UPDH_1J289P$

Why does the professor mention icing on a cake? A. To stress how easy it is to use the impasto technique B. To claim that impasto involves the application of thin layers of paint C. To make it clear that impasto should have a flat surface D. To describe the type of appearance that impasto gives to a painting