Whenever information or assistance requested under subparagraph (A) or (B) of paragraph (1) is, in the judgment of the Board, unreasonably refused or not provided, the Board shall report the circumstances to the head of the department, agency, or element concerned without delay. The head of the department, agency, or element concerned shall ensure that the Board is given access to the information, assistance, material, or personnel the Board determines to be necessary to carry out its functions.