单项选择题

Questions 4 to 7 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions.
Now listen to the conversation.

Which of the following is true about Potter

A.He is a postgraduate.
B.He is qualified for teaching postgraduates.
C.He is an expert in town planning.
D.He has only given one undergraduate course so far.