Last Year,five-Year-Old Emily Began a Bedtime Ritual That Frustrated Her

Last year,five-year-old Emily began a bedtime ritual that frustrated her parents.Shortly after being put to bed for the evening,Emily would begin a series of requests: "I need a drink of water." "Please read me another story." "I think something is under my bed.Come look!" Emily's parents finally resolved that they would not respond to Emily and warned her that once she went to bed,she was expected to go quietly to sleep.Through a long and difficult week,Emily's parents held firm and ignored her pleas and tears.Now,Emily drifts peacefully and quickly to sleep when she is put to bed.Emily's parents practiced the learning principle of

A) punishment.
B) extinction.
C) positive reinforcement.
D) modelling.