; and (ii) the assurances required under subparagraph (D). (C) Sustainability plan The Secretary shall require a State educational agency submitting an application under subparagraph (B) to provide a plan that demonstrates how, following the conclusion of the 4-year grant period, such agency will continue to maintain and adjust the annual base minimum salary in accordance with subsection (b). (D) Required assurances The Secretary shall require a State educational agency submitting an application under subparagraph (B) to provide an assurance in such application that— (i) if necessary to achieve the purpose of this section, the State will enact and enforce legislation to establish a statewide teacher salary schedule or otherwise to establish minimum teacher salary requirements; (ii) each teacher described in paragraph (1) will be compensated on a salary basis at an annual rate per school year that is not less than the salary threshold described in subsection (b); (iii) each teacher who is employed part-time at a qualifying school in a State will be compensated on a salary basis at an annual rate per school year that is not less than the salary threshold described in subsection (b), proportionately reduced in accordance with the number of hours worked by such teacher; (iv) priority will be given to local educational agencies in accordance with subparagraph (E)(ii)