TOEFL Listening: TPO-TOEFL听力TPO - GF1961INXS5B1SMWR$

What does the professor mean when he says this: A. He will not be able to complete his discussion of the crystallization process today. B. He is going to present information differently from how he had originally planned. C. He forgot that he had already told the class what the four processes are. D. He will discuss all four processes in class today.