Answer:
Answer is 2. Learning.
Explanation:
Learning can be explained or described as the process by which life experience causes change in the behavior or thinking of an organism.
In this case, the normal behavior of the dog is to be quiet , this is how it behaves normally. But as time goes on, it learnt that whenever the doorbell is rung, it signifies the arrival of people.
This is a change in behavior that occurred through the experiences it had heard over the course of several weeks. This signifies a learning process.
