Which of the following is covered by Medicare Part B?

Medicare Part B primarily covers outpatient services, including various forms of medical care and preventive services. Home health care services fall under this umbrella when they meet specific criteria established by Medicare. This typically includes services like intermittent skilled nursing care, physical therapy, and certain health-related services that can be provided in the home, given that they are deemed medically necessary.

The focus of Medicare Part B coverage is on outpatient care rather than inpatient or long-term institutional care. While emergency room visits are covered, they are not the sole focus of Part B. Additionally, prescription drugs are generally covered under Part D, not Part B, and long-term nursing care is generally not covered under Medicare at all. Therefore, home health care services is the correct answer as it directly relates to the core services provided by Medicare Part B as part of its aim to support medical needs outside of hospital settings.