Which of the following is NOT a major subsystem of the U.S. Health System?

The traditional healthcare model is considered a historical concept rather than a major subsystem in the contemporary U.S. healthcare system. The major subsystems are more defined and operational in today's health landscape. Managed care systems focus on controlling healthcare costs while providing quality services through a network of providers. The public health system emphasizes the health of populations, concentrating on disease prevention and health promotion. Behavioral care systems specifically cater to mental health and substance use disorders, addressing a vital component of overall health.

While the traditional healthcare model provided a framework in earlier years, today's healthcare system operates through these more specialized and integrated subsystems that respond to current challenges and priorities in health delivery. Therefore, identifying the traditional healthcare model as not being a major subsystem is accurate, as it does not encapsulate the dynamics present in modern healthcare delivery and management.