appropriate
(3) Medicare administrative contractor defined For purposes of this subchapter and subchapter XI— (A) In general The term “medicare administrative contractor” means an agency, organization, or other person with a contract under this section. (B) Appropriate medicare administrative contractor With respect to the performance of a particular function in relation to an individual entitled to benefits under part A or enrolled under part B, or both, a specific provider of services or supplier (or class of such providers of services or suppliers), the “appropriate” medicare administrative contractor is the medicare administrative contractor that has a contract under this section with respect to the performance of that function in relation to that individual, provider of services or supplier or class of provider of services or supplier.