A、On a bus. B、On a train. C、Over a phone. D、In an elevator. D

M: Miss Smith, I told Dr. Brown that I would call him in the Houston office at ten o’clock their time. Please find out the time difference for me so that I’ll know when to place the call.
W: It’s two hours earlier in Houston, Sir. I know without looking it up because my sister lives there.
Q: When should the man place his call to Houston?

W: Nine, please.
M: This is the express, Madam. The first stop is the first floor.
Q: Where did this conversation take place?