Final answer:
A governmental agency like Health and Social Services is not a necessary building block of a health care system.
Step-by-step explanation:
The correct answer is d. A governmental agency like Health and Social Services. While a nonprofit health organization, a private hospital, and a government agency are all important building blocks of a health care system, a governmental agency like Health and Social Services is not a necessary component.
Governments can provide health care services directly through their own agencies or indirectly by regulating and funding private health care providers, but the existence of a specific government agency like Health and Social Services is not essential to the functioning of a health care system.