Final answer:
Medicare Part A covers skilled nursing facility care for up to 100 days per spell of illness, which is not listed among the given multiple-choice options.
Step-by-step explanation:
The duration of skilled nursing facility Medicare Part A coverage is limited to the need for daily skilled care up to a maximum of 100 days per spell of illness. Thus, the correct answer to the student's question is not explicitly stated among the options given (a. 60 days, b. 90 days, c. 120 days, d. 150 days), as the actual coverage duration provided by Medicare Part A is 100 days. It's important for students studying healthcare administration, health policy, or gerontology to understand the specifics of Medicare coverage as it is a critical part of the US healthcare system.