Sorensen Systems Inc. is expected to pay a $3.00 dividend at year end (D1 = $3.00), the dividend is expected to grow at a constant rate of 4.00% a year, and the common stock currently sells for $77.50 a share. The before-tax cost of debt is 6.50%, and the tax rate is 25%. The target capital structure consists of 45% debt and 55% common equity. What is the company's WACC if all the equity used is from retained earnings? Do not round your intermediate calculations. O a. 6.61% O b. 6.37% O c. 6.52% O d. 6.22% O e. 5.44%