Answer:
Foot-in-the-door phenomenon.
Step-by-step explanation:
Foot-in-the-door phenomenon: In psychology, the phenomenon of foot-in-the-door is referred to as the process of making a small request from someone initially to make the person agrees later on for a big request. It gives an idea that if an individual agrees for a small request then he or she might agree for the bigger one as well.
Example: A child request to get a small toy from his or her parents and then, later on, ask for a cycle.
In the question above, Bart's experience best illustrates the foot-in-the-door phenomenon.