Questions 4 to 6 are based on the following conversation. At the end of the conversation, you will be given 15 seconds to answer the questions. Now, listen to the conversation. Why does the man say this "He’s an expert on the natural history of the region and has written several books on the topic. "
A．To emphasize the professor’s qualifications. B．To state a desire to read the professor’s books. C．To predict that the seminar attendance will be high. D．To imply that the seminar needs improvement.