Dr. Nwoambi is a psychologist who is currently evaluating a new client. Dr. Nwoambi would most likely refer to the __________ to assist her in diagnosing her client's psychological disorder.

A) Diagnostic and Statistical Manual of Mental Disorders
B) Physician's Desk Reference
C) Textbook of Psychological Disorders
D) Textbook of Physiological Disorders

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the standard reference used by mental health professionals in the United States to diagnose mental health and behavioral conditions. It provides criteria and descriptions of various disorders and helps clinicians arrive at an accurate diagnosis for their patients. The Physician's Desk Reference is a resource for medications and their side effects, not for diagnosing psychological disorders. Textbooks may provide information about psychological disorders, but they are not as comprehensive or specific as the DSM. Textbooks of physiological disorders focus on physical health conditions, not mental health.