XYZ Inc.'s target capital structure is 30% debt, 15% preferred, and 55% 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. O a. 5.95% O b.7.88% O c. 6.77% O d. 6.42% O e. 6.61%