; and (B) protect, preserve, and improve collateral held by the Secretary to secure indebtedness. (2) Audits The financial transactions of the Secretary under paragraph (1) shall be audited by the Comptroller General. The Comptroller General shall allow credit for an expenditure shown to be necessary because of the nature of the business activities authorized by this section or subtitle V of title 46. At least once a year, the Comptroller General shall report to Congress any departure by the Secretary from this section or subtitle V of title 46. (i) Grant administrative expenses Except as otherwise provided by law, the administrative and related expenses for the administration of any grant programs by the Maritime Administrator may not exceed 3 percent. (j) Authorization of appropriations (1) In general Except as otherwise provided in this subsection, there are authorized to be appropriated such amounts as may be necessary to carry out the duties and powers of the Secretary relating to the Maritime Administration. (2) Limitations Only those amounts specifically authorized by law may be appropriated for the use of the Maritime Administration for— (A) acquisition, construction, or reconstruction of vessels; (B) construction-differential subsidies incident to the construction, reconstruction, or reconditioning of vessels; (C) costs of national defense features; (D) payments of obligations incurred for operating-differential subsidies; (E) expenses necessary for research and development activities, including reimbursement of the Vessel Operations Revolving Fund for losses resulting from expenses of experimental vessel operations; (F) the Vessel Operations Revolving Fund; (G) National Defense Reserve Fleet expenses; (H) expenses necessary to carry out part B of subtitle V of title 46