Final answer:
Roster billing applies to Medicare Part B, covering services outside of hospital stays such as doctor visits and outpatient services.
Step-by-step explanation:
Roster billing is a method used in Medicare Part B, which is the part that provides coverage for health-care costs outside of hospital stays, such as physician services, medical tests, and outpatient visits. Under Medicare Part B, participants are responsible for a monthly fee, deductible charges, and copayments, with the government subsidizing about three-fourths of the overall costs.