You were hired as a consultant to QQQ Company, whose target capital structure is 40% debt, 10% preferred, and 50% common equity. The interest rate on new debt is 6%, the yield on the preferred is 5%, the cost of retained earnings is 13%, and the tax rate is 40%. The firm will not be issuing any new stock. What is QQQ Company's WACC? Select one: a. 9.67% b. 9.34% c. 8.98% d. 8.44%