A Teacher Tells Her First Graders That Whenever the Bell

Multiple Choice

A teacher tells her first graders that whenever the bell on her clock rings, the students who are in their seats will each receive one token to put in their "happy jars." She then says, "No one knows when the clock will ring. It might be ten minutes, it might be 17 minutes, or only five minutes; so you better be in your seat." The teacher is using which schedule of reinforcement for "in-seat" behavior?

A) fixed ratio
B) fixed interval
C) variable ratio
D) variable interval