Final answer:
To enroll in Medicare Supplements, clients must have both Medicare Part A and Part B. Part A covers hospital charges and Part B covers other health-care costs outside hospital stays.
Step-by-step explanation:
Clients who want to enroll in Medicare Supplements, also known as Medigap policies, are required to have both Medicare Part A and Part B. Part A primarily covers hospital charges and is funded by payroll deductions, whereas Part B is an optional insurance system covering healthcare costs outside of hospital stays, such as physician services and outpatient visits. Since Medicare's inception in 1965, it has been a crucial program for providing health insurance to the elderly, covering millions of Americans.