请根据下面短文回答： —Buses leave the Railway Station, New York City, from 7:00 a.m. and then every half-hour, until 11:30 p.m. (7 days a week) —Evening rush-hours(5:00 p.m. to 7:00 p.m.): Buses leave the Railway Station, New York City, every 15 minutes. (Monday to Friday) —Holidays: Buses leave every hour on the hour. (Trip time: 30 minutes each way) —All tickets must be bought at Window 12, the Railway Station, New York; or at the Brennan Station Window. What does it mean by "Buses leave every hour on the hour"
[A] Buses leave every two hours. B. Buses leave every one and half hours. C. Buses leave every hour such as nine o’clock, ten o’clock, and so on.