You were hired as a consultant to Quigley Company, whose target capital structure is 35% debt, 10% preferred, and 55% common equity. The interest rate on new debt is 6.50%, the yield on the preferred is 6.00%, the cost of retained earnings is 10.50%, and the tax rate is 25%. The firm will not be issuing any new stock. What is Quigley's WACC? Round final answer to two decimal places. Do not round your intermediate calculations. a. 6.73% b. 9.37% c. 8.08% d. 6.97% e. 6.11%