On Monday, Johnny's mother gave him cookies and milk after he had played quietly for 10 minutes. On Tuesday, she required 20 minutes of quiet play before treat time, and on Wednesday, the cookies were given to him only after a full half hour of quiet play. Johnny was taught to play quietly for extended periods through:. a. modeling. b. latent learning. c. partial reinforcement. d. shaping.

.d. shaping.

Explanation:

Shaping, also referred to as " successive approximations "is the step by step systematic reinforcement of a target behavior, of which each step brings one closer until that target desired behavior is achieved,

Here, the trainer's role is to ensure  assistance and guidance to his or her subject in setting goals to achieve a desired behavior.

Shaping even though employed in the training of domestic pets lie dogs, cats etc have been efficiently used to reinforce desired behavior in human especially at an early age, In the question above,, we can see that Johnny's mother used a step by step successive approach to Shape Johnny  to a desired behaviour.

i got 3,4 and 5 as an answer