A、Two rooms. B、Three rooms. C、Five rooms. D、Six rooms. C问题问的是男士订了几个房间。根据男士所说Two single rooms and three double rooms可知,男士一共定了5个房间

W：Bright Star Hotel.
M：Good afternoon.My name is Martin.I’d like to book some rooms for tomorrow for a week.
W：OK.What kind of rooms would you like?
M：Two single rooms and three double rooms.
W：Sure, we have single rooms at $ 30，$ 40 a night and double rooms at $ 40, $ 50 a night.
M：Fine.I would like single rooms at $ 40 and double rooms at $ 50.
W：So, two single rooms at $ 40 a night and three double rooms at $ 50 a night.
M：Yes, that’s right.Thank you.
W：You’re quite welcome.
Q17：How long does the man book the rooms?
Q18：How many rooms does the man book?
Q19：How much will the man pay for one night?