Final answer:
Classic signs and symptoms of phobias, including agoraphobia, are characterized by severe anxiety and fear.
Step-by-step explanation:
Classic signs and symptoms of phobias, including agoraphobia, are characterized by severe anxiety and fear. These symptoms can manifest as panic attacks, an overwhelming sense of dread, and avoidance of certain situations or places. Other symptoms such as insomnia and an inability to concentrate may be associated with anxiety disorders, but they are not specific to phobias.