M: Excuse me. Have you been waiting longW: Twenty minutes already.M: Did you notice whether the No. 7 bus has passed byW: Not while I’ve been standing here. I’m also waiting for the No. 7 bus myself.M: Good. Hot today, isn’t itW: Yes, it is. I wish that it would rain and cool off.M: Me, too. This is unusual for March. I don’t remember it ever being so hot and dry in March before.W: My mother and I have just moved here from Indiana. It is pretty cold there.M: Yes, I’ve heard of that.W: Do you think we’ve missed the busM: Take it easy. It never comes exactly on the half hour like it should. How often should the bus come to their stop()
A. Every twenty minutes.
B. Every half an hour.
C. Once a day.