You were hired as a consultant to Giambono Company, whose target capital structure is 55% debt and 45% common equity. The after-tax cost of debt is 6.00%, the cost of preferred is 7.50%, and the cost of equity is 12.00%. The firm will not be issuing any new stock. What is its WACC (after tax)? O a. 11.25% b. 8.50% c.5.40% d. 8.70%