英语翻译Buses going to the town center will leave the gate every

英语翻译
Buses going to the town center will leave the gate every hour on the half hour during the day.
关于这句话的一个问题
At which of the following times will the bus leave the gate?
A.8:00 ,9:00 ,10:00 ,11:00
B.8:30,9:30,10:30,11:30.
c.8:00 ,9:00 ,10：30,11:00
8:00 ,9:30 ,10:00 ,11：30
应该是B吧?》