For Alexis, cocaine is the unconditioned stimulus, the phone call is the neutral stimulus, and the conditioned stimulus is the phone call.
An unconditioned stimulus is a special type of stimulus in the brain that generates an automatic response.
For example, when a person smells his/her favorite food, he/she immediately has hunger as a response to an unconditioned stimulus.
Conversely, a conditioned stimulus does not produce an automatic response in the brain.
Learn more about unconditioned stimulus here:
https://brainly.com/question/24868138