Final answer:
The most commonly diagnosed cluster of mental disorders in the USA is anxiety disorders. This includes OCD, panic disorders, PTSD, and phobias.
Step-by-step explanation:
The most commonly diagnosed cluster of mental disorders in the USA is anxiety disorders. Almost 18 percent of U.S. adults are likely to be affected in a single year, and 28 percent are likely to be affected over the course of a lifetime (Anxiety and Depression Institute of America 2021). Anxiety disorders include obsessive compulsive disorder (OCD), panic disorders, posttraumatic stress disorder (PTSD), and both social and specific phobias.