Edward Adamson's population consisted of:

• A. Patients in psychiatric hospital
• B. Children in schools
• C. Outpatients in clinics
• D. Private clients

Answer: (A)

Edward Adamson pioneered art therapy within psychiatric care, focusing on patients in hospital settings. He established the first formal art therapy service in a psychiatric hospital (not in schools, outpatient clinics, or private practice), using art as a means to access and express internal experiences of those with chronic mental illness during inpatient treatment. This inpatient, hospital-based population is why the correct understanding is that his work centered on patients in psychiatric hospital settings.