The trip to the Mystery Caves will take place on Sunday, 27 July. You can book your ticket

s in Room 188 between 2:30 p.m. and 4:00 p.m. every day. Your parents should confirm (确认) the booking by writing to us as soon as possible. You should pay for the trip before 21 July. If we do not receive your money early enough, your booking will be cancelled(取消). If the trip does not take place for any reason, your money will be paid back.

We are planning to meet outside the railway station on Black Street at 8:00 a.m. It will take us about 2 hours to get to the center of the town by train, and from there we have to catch a bus. It will take another hour to get to the Mystery Caves on the bus.

We will spend about 1 hour and a half visiting the caves (山洞), and we hope to catch the 1:30 bus to Happy Lake for some swimming. If we are late, we will have to take the 3:00 bus straight back to Black Street.

When must you pay for the ticket？

A．At any time before the trip.

B．One week before the trip.

C．Three days before the trip.