Allison Engines Corporation has established a target capital structure of 40 percent debt and 60 percent common equity. The current market price of the firm's stock is PO = $42.7; its last dividend was DO = $5.7, and its expected dividend growth rate is 6 percent. What will Allison's marginal cost of retained earnings, rs, be? O 17.15% 0 19.15% 0 20.15% 16.15% 18.15%