【单选题】

{{I}}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.{{/I}} In a distance learning course, one ____.

A、does not have to see the professors
B．also needs to take exams
C．reduces the learning expenses
D．must revise the schedule to attend the course