; and (3) sign a written agreement to serve on active duty, or, if on active duty, to remain on active duty for a period in addition to any other incurred active duty obligation. (c) Academic and professional requirements One of the following academic requirements must be satisfied for purposes of determining the eligibility of an individual for a loan repayment under this section: (1) The person is fully qualified in a profession that the Secretary has determined to be necessary to meet identified skill shortages in the commissioned officer corps. (2) The person is enrolled as a full-time student in the final year of a course of study at an accredited educational institution (as determined by the Secretary of Education) leading to a degree in a profession that will meet identified skill shortages in the commissioned officer corps. (d) Loan repayments (1) In general Subject to the limits established under paragraph (2), a loan repayment under this section may consist of the payment of the principal, interest, and related expenses of a loan obtained by a person described in subsection (b). (2) Limitation on amount For each year of obligated service that a person agrees to serve in an agreement described in subsection (b)(3), the Secretary may pay not more than the amount specified in section 2173(e)(2) of title 10, United States Code. (e) Active duty service obligation (1) In general A person entering into an agreement described in subsection (b)(3) incurs an active duty service obligation. (2) Length of obligation determined under regulations (A) In general Except as provided in subparagraph (B), the length of the obligation under paragraph (1) shall be determined under regulations prescribed by the Secretary. (B) Minimum obligation The regulations prescribed under subparagraph (A) may not provide for a period of obligation of less than 1 year for each maximum annual amount, or portion thereof, paid on behalf of the person for qualified loans. (3) Persons on active duty before entering into agreement The active