What role does a teacher play in the following activity?
 
T: Do you have any hobbies?
 
S: Yes, I like singing and dancing.
 
T: Uhm, and.?
 
S: I also collect coins.
 
T: Oh, really, how many..have you already.. collected?
 
A、Controller
B、Assessor
C、Organizer
D、Prompter