Answer: A conditioned stimulus
Explanation:
A conditioned stimulus is one of the type of classical conditioning process in which it basically explain about the various types of learning theory as it basically helps in determining the various types of response and also triggering the various types of conditioned response.
According to the given question, In the given learned association, the candy bar is basically serves in the form of a conditioned stimulus. The conditioned response is also known as the response triggering process.
Therefore, A conditioned stimulus is the correct answer.