Answer:
C.
Step-by-step explanation:
Fear extinction is the process of countering the fear-conditioned response.
According to the experiment of Little Albert, a person's fear becomes a conditioned response when neutral stimulus was added with the unconditioned stimulus.
To eliminate the conditioned response of fear, the psychologists create a scenario that exposes the person to fear-eliciting cue but eliminates aversive events. This process is called fear extinction.
In the given scenario, the disappearing of Ashley's fear of clowns over the period is an example of fear extinction.
So, the correct answer is extinction.