Answer:
Shaping.
Step-by-step explanation:
Shaping may be defined as the phenomena that are primarily used for the experimentation analysis of the behavior. The response gets changed after the successive stimulus of the individual.
Johnny's response get changed day by day as he gets he repeated stimulus daily. The milk and cookies acts as the stimuli and different time of quiet play represent his response. The frequency of the Johnny's behavior is increasing day by day as the response become frequent in shaping.
Thus, the answer is shaping.