You were hired as a consultant to Keys Company, and you were provided with the following data: Target capital structure: 40% debt, 10% preferred, and 50% common equity. The after-tax cost of debt is 4.00%, the cost of preferred is 7.50%, and the cost of retained earnings is 11.50%. The firm will not be issuing any new stock. What is the firm's WACC?
a) 7.55%
b) 7.73%
c) 7.94%
d) 8.10%
e) 8.32%