Answer:
Extinction
Step-by-step explanation:
Extinction is a recognized behavioral phenomenon capable of making a person to gradually adapt to a continuously changing environment. When a learned behavior begins to decrease in strength when there is no reinforcement. From the question, we can see that John and Darrin did not reinforce the behavior of welcoming Lee and thus gradually Lee began to adapt to a changing environment and reacted according to the situation by avoiding John and Darrin.