Final answer:
Fred is most likely to be diagnosed with a specific phobia, an anxiety disorder characterized by an intense fear and avoidance of certain objects or situations.
Step-by-step explanation:
Fred is most likely to be diagnosed with an anxiety disorder, specifically a specific phobia. Specific phobias are characterized by an intense fear and avoidance of certain objects or situations. In Fred's case, his fear of leaving his house and apprehension when going out in public indicate a specific phobia.
It is important to note that specific phobias can be treated with therapy, such as cognitive-behavioral therapy (CBT), and medication if necessary. Seeking professional help from a mental health professional would be beneficial for Fred to address and manage his anxiety disorder