; or (B) rehabilitating a bridge. (2) Types of assistance On application by a State or States to the Secretary, the Secretary may approve Federal assistance for any of the following activities for a highway bridge that has been determined to be eligible for replacement or rehabilitation under subsection (b): (A) Painting. (B) Seismic retrofit. (C) Systematic preventive maintenance. (D) Installation of scour coun­ter­mea­sures. (E) Application of calcium magnesium acetate, sodium acetate/formate, or other environmentally acceptable, minimally corrosive anti-icing and de-icing compositions. (3) Basis for determination The Secretary shall determine the eligibility of highway bridges for replacement or rehabilitation for each State based on highway bridges found to be in poor condition in the State. (4) Special rule for preventive maintenance Notwithstanding any other provision of this subsection, a State may carry out a project under paragraph (2)(B), (2)(C), or (2)(D) for a highway bridge without regard to whether the bridge is eligible for replacement or rehabilitation under this section. (5) Apportionment (A) In general Funds authorized to carry out this section shall be apportioned among the several States on October 1 of the fiscal year for which authorized in accordance with this subsection. (B) Categories of deficiency Each deficient bridge shall be placed into one of the following categories: (i) Federal-aid system bridges eligible for replacement. (ii) Federal-aid system bridges eligible for rehabilitation. (iii) Off-system bridges eligible for replacement. (iv) Off-system bridges eligible for rehabilitation. (C) Calculation of apportionment (i) In general The deck area of deficient bridges in each category shall be multiplied by the respective unit price on a State-by-State basis, as determined by the Secretary, and the total cost in each State divided by the total cost of the deficient bridges in all States shall determine the apportionment factors. (ii) Determinations The Secretary shall make