studies of alternative aircraft inventories through 2030, and an associated force-sizing construct, for the Air Force. (2) Submittal to Congress Not later than March 1, 2019, the Secretary shall submit the results of each study to the congressional defense committees. (3) Form The result of each study shall be submitted in unclassified form, but may include a classified annex. (b) Entities To perform studies The Secretary shall provide for the studies under subsection (a) to be performed as follows: (1) One study shall be performed by the Secretary of the Air Force, in consultation with the Director of the Office of Net Assessment. (2) One study shall be performed by a federally funded research and development center. (3) One study shall be conducted by an independent, nongovernmental institute which is described in section 501(c)(3) of the Internal Revenue Code of 1986 and exempt from taxation under section 501(a) of such Code, and has recognized credentials and expertise in national security and military affairs. (c) Performance of studies (1) Independent performance The Secretary shall require the studies under this section to be conducted independently of one another. (2) Matters to be considered In performing a study under this section, the organization performing the study, while being aware of current and projected aircraft inventories for the Air Force, shall not be limited by such current or projected aircraft inventories, and shall consider the following matters: (A) The national security and national defense strategies of the United States. (B) Potential future threats to the United States and to United States air and space forces through 2030. (C) Traditional roles and missions of the Air Force. (D) Alternative roles and missions for the Air Force. (E) The force-sizing methodology and rationale used to calculated aircraft inventory levels. (F) Other government and nongovernment analyses that would contribute to the study through variations in study assumptions or potential scenarios. (G) The role of