Questions 17—20 are based on the following talk on booking tickets. You now have 15 seconds to read questions 17—20. Which of the following can be inferred from the talk

A．Mr. Cotton should come to the ticket office as soon as possible.
B．Mr. Cotton gets the ticket at once.
C．Mr. Cotton will get the ticket in the local post office.
D．Mr. Cotton needs to go to the ticket office to get the ticket.