1-94Fred Refuses to Speak at School,although He Speaks Normally at Home.His

1-94.Fred refuses to speak at school,although he speaks normally at home.His therapist plans out a treatment where Fred is given a gold star every time he answers his teacher,and he can then trade in his stars for prizes.Fred begins speaking in class.The therapist then tells the teacher to stop the program for a couple of weeks.Fred stopped talking during that time.The teacher then starting giving Fred stars again,and Fred again began to talk.This is an example of

A) a case study.
B) a correlational study.
C) an ABAB experimental design study.
D) a self-report study.