As a financial analyst for a firm looking to make an investment in its operations, you are tasked with determining how upcoming projects are financed. Because the board of directors decided years ago that it would not offer preferred stock, the firm is comprised of only debt and equity financing. Given the following analysis of optional capital structures, which is the optimal capital structure?

$\backslash$table$[[\backslash$table$[[$Proportion of Debt$],[$Financing$]],\backslash$table$[[$After$-$Tax Cost$],[$of Debt$]],\backslash$table$[[$Cost of$],[$Equity$]],\backslash$table$[[$Weighted$],[$Cost$]]],[0\%,5\%,9\%,9\mathrm{.}00\%$