(D)
any loan incurred for educational purposes made by a lender that is—
(i)
an agency or instrumentality of a State;
(ii)
a financial or credit institution (including an insurance company) that is subject to examination and supervision by an agency of the United States or any State;
(iii)
a pension fund approved by the Secretary for purposes of this section; or
(iv)
a nonprofit private entity designated by a State, regulated by that State, and approved by the Secretary for purposes of this section.
Repayment of any such loan shall be made on the basis of each complete year of service performed by the borrower.