Marginal Incorporated (MI) has determined that its after-tax cost of debt is 10.0%. Its cost of preferred stock is 14.0%. Its cost of internal equity is 16.0%, and its cost of external equity is 21.0%. Currently, the firm's capital structure has $372 million of debt, $30 million of preferred stock, and $198 million of common equity. The firm's marginal tax rate is 25%. The firm is currently making projections for the next period. Its managers have determined that the firm should have $70 million available from retained earnings for investment purposes next period. What is the firm's marginal cost of capital at a total investment level of $255 million? 10.63% 12.18% 13.01% 12.28% 13.83%