ABC Inc.'s target capital structure is 60% debt, 15% preferred, and 25% common equity. The interest rate on new debt is 5.50%, the yield on the preferred is 6.5%, the cost of retained earnings is 7.25%, and the tax rate is 40%. The firm will not be issuing any new stock. What is the WACC? Do not round your intermediate calculations. a. 4.77% b. 5.56% C. 6.77% d. 6.35% e. 7.88%