Final answer:
The DSM-5 is a classification and diagnostic guide for mental disorders, including substance use and personality disorders, but it is not used for billing treatment.
Step-by-step explanation:
The DSM-5 or the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, serves multiple important roles in the field of psychology and psychiatry. The DSM-5 is A) a classification system of psychological disorders and B) a guide to diagnosing psychological disorders. It contains criteria for diagnosing a wide range of psychological conditions, including substance use disorders, personality disorders, and more. While the DSM-5 is utilized for diagnostic purposes, it does not function as C) a system for billing treatment of psychological disorders. This manual is widely used by mental health professionals to ensure consistency in diagnosis across different practitioners and settings.