A、At 5:30. B、At 6:00. C、Before 6: 00. D、After 6: 00. D

W: I’ve got to make a phone call. There is a phone-box over there.
M: Now it is 5:30 already. Why don’t you make a call later. It is cheaper after 6 p.m.
W: Is it? Oh, good. I thought it cost the same. I’ll wait till I get home then. Where can you find out how much phone calls cost?
M: You can find it at the front of any telephone directory.
W: Ah, I must have a good look. Does it give any other information?
M: Yes, you will get any information you need, such as the weather forecast, gardening information, etc.
W: Good. I’ll have a look. How can I arrange an alarm call? My brother’s arriving from Paris early tomorrow and I must get to the airport very early in the morning.
M: Well. You’d better book before 10:30 p.m. the previous evening.
W: That seems simple enough. Actually I think I’ll phone my brother this afternoon. I’ve got the phone number of his hotel, but what if he isn’t in when I phone? It could be expensive and I can’t afford to keep phoning all afternoon.
M: Well. You could make a personal call. You can tell the operator your brother’s name, then your message can be left for your brother and you would not pay any money until you talk to him.
W: Perfect. I’ll do that. Thank you, Alan.