this subparagraph and subparagraph (K): (I) Part D biosimilar biological product The term part D biosimilar biological product means a covered part D drug that is a biosimilar biological product (as defined in section 1847A(c)(6)(H)). (II) Part D generic drug The term part D generic drug means a covered part D drug that is approved under section 505(j) of the Federal Food, Drug, and Cosmetic Act. (III) Part D reference biological product The term part D reference biological product means a covered part D drug that is a reference biological product (as defined in section 1847A(c)(6)(I)). (IV) Part D reference drug The term part D reference drug means, with respect to a part D generic drug, a covered part D drug that is the listed drug (as described in clause (i) of section 505(j)(2)(A) of the Federal Food, Drug, and Cosmetic Act) that is referred to in the abbreviated application for such part D generic drug under such section. (V) Wholesale acquisition cost The term wholesale acquisition cost has the meaning given such term in section 1847A(c)(6)(B). (K) Cost-Sharing tiering requirements with respect to part D generic drugs and part D biosimilar biological products (i) Generic drug and biosimilar biological product cost-sharing tier With respect to a plan year beginning on or after January 1, 2025, if the PDP sponsor offering the prescription drug plan applies tiered cost-sharing (through copayment or coinsurance tiers) to covered part D drugs on a formulary, the PDP sponsor shall— (I) have at least one cost-sharing tier on the formulary that only includes part D generic drugs and part D biosimilar biological products