A single-trip ticket or ________is often used by tourists. It can be used only one time on the day you buy it within the subway lines and stations you choose. It should be returned at your destination station and recycled in the ticket system. 单程票或者________经常被游客使用。您只能在购买当天在您选择的地铁线路和车站内使用一次。此代币须在您的在目的地站须归还，并在票务系统回收。
A、coin 硬币
B、token 代币
C、paper ticket 纸质票