Under what circumstances can Mrs. Kelly enroll in a stand-alone Medicare prescription drug plan while having a Medicare Advantage plan?

The correct circumstance under which Mrs. Kelly can enroll in a stand-alone Medicare prescription drug plan while having a Medicare Advantage plan is when she chooses a Private Fee-for-Service (PFFS) plan without drug coverage.

When enrolled in a Medicare Advantage plan, beneficiaries typically receive their medical and prescription drug benefits through that plan. However, if a beneficiary is in a Medicare Advantage plan that does not include drug coverage, they have the option to enroll in a stand-alone Medicare prescription drug plan. This is particularly relevant for PFFS plans, as they can be structured to allow for this flexibility, giving beneficiaries the opportunity to obtain prescription drug coverage that may be lacking in their current Medicare Advantage plan.

In contrast, if someone selects a Medicare Advantage plan that includes drug coverage, they cannot select a stand-alone drug plan. Similarly, PPO plans with drug coverage would not allow this dual enrollment with a separate drug plan. The other options imply scenarios that do not provide the essential gap that allows for the enrollment in a stand-alone drug plan, as they either contradict the nature of coverage provided by Medicare Advantage or are not applicable under Medicare's enrollment rules.