Final answer:
Medicare is the U.S. healthcare system that operates as a single-payer system, primarily offering insurance to individuals over sixty-five years of age.
Step-by-step explanation:
The health care system in the U.S. that has a single-payer healthcare system is Medicare, which provides insurance primarily to people over sixty-five years old. It's a tax-supported system designed to cater to the elderly, who face higher average health care costs. Unlike Medicare, Medicaid is a program jointly funded by states and the federal government that provides health care to those with low incomes, and the Veterans Health Administration functions as a socialized system specifically for military veterans. The Affordable Care Act (Obamacare) aimed to provide all Americans with access to affordable health insurance and is not a single-payer system.
Medicare is a government-funded program that provides health insurance primarily to people over sixty-five years old. It is a tax-supported, single-payer system for the elderly in the United States.