(i) Enrollees in a plan providing qualified prescription drug coverage receive coverage through the plan A part D eligible individual who is enrolled in an MA–PD plan obtains such coverage through such plan.
(ii) Limitation on enrollment of MA plan enrollees in prescription drug plans Except as provided in clauses (iii) and (iv), a part D eligible individual who is enrolled in an MA plan may not enroll in a prescription drug plan under this part.
(iii) Private fee-for-service enrollees in MA plans not providing qualified prescription drug coverage permitted to enroll in a prescription drug plan A part D eligible individual who is enrolled in an MA private fee-for-service plan (as defined in section 1395w–28(b)(2) of this title ) that does not provide qualified prescription drug coverage may obtain qualified prescription drug coverage through enrollment in a prescription drug plan.
(iv) Enrollees in MSA plans permitted to enroll in a prescription drug plan A part D eligible individual who is enrolled in an MSA plan (as defined in section 1395w–28(b)(3) of this title ) may obtain qualified prescription drug coverage through enrollment in a prescription drug plan.