A stock has just paid $4 of dividend. The dividend is expected to grow at a constant rate of 12% a year, and the common stock currently sells for $70. The before-tax cost of debt is 10%, and the tax rate is 20%. The target capital consists of 37% debt and 63% common equity. What is the companys WACC if all the equity used is from retained earnings?

a. 13.53%

b.15.13%

c.13.68%

d.15.86%

e.14.55%