Answer:
shaping
Step-by-step explanation:
Shaping: In psychology, the term "shaping" is described as a phenomenon that involves the reinforcement process that is being administered repeatedly and is successively getting closer and closer to the approximations that give rise to the desired behavior.
The shaping techniques is considered as one of the behavioral modification techniques.
In the question above, Darren is using shaping to get his son to eat his peas.