Conversation 2[听力原文] 8-10W: Good morning, sir. May I help youM: Yes, would you please find a room for our business meetingW: Certainly, sir. How many people do you haveM: Well, about 10.W: Fine. We have a conference room which can seat up to 20 people.M: That’s great. What about the chargeW: It is 90 RMB per hour. There is no minimum charge. Do you want to book itM: Yes, I think so.W: May I have your name and room number, please, sirM: Mr. Black, Room 1208.W: Thank you, Mr. Black. How 10ng will you be using the conference roomM: We’ll start at 10 o’clock tomorrow morning but I’m not sure when we’ll finish.W: No problem, Mr. Black. The room will be at your disposal then. What’s the probable relationship between the two speakers（）

A. Clerk and guest.
B. Shop assistant and customer.
C. Employer and employee.
D. Store keeper and customer.