Final answer:
Medicare Part D covers medications that are listed on its formulary. This is the chief condition for a medication to be paid for by Medicare Part D.
Step-by-step explanation:
The condition that must be met for Medicare Part D to pay for a medication is C. Must be on the Medicare Part D formulary. Medicare Part D is the component of Medicare that provides prescription drug coverage. In order for a medication to be covered, it must be listed on the plan's formulary, which is essentially a list of medications that are covered by the program. These are typically drugs that are considered necessary and cost-effective. Coverage for over-the-counter medications, specialist prescriptions, or hospital administration are not inherent requirements for Medicare Part D coverage.