A firm has $$60$ million of common stock, $$40$ million of preferred stock, and $$80$ million of debt. The cost of equity is $8\mathrm{.}5\%,$ the cost of preferred stock is $9\mathrm{.}5\%,$ and the pre$-$tax cost of debt is $7\%.$ If the firm's tax rate is $30\%,$ what is the firm's WACC?

A$)7\mathrm{.}75\%$

B$)8\mathrm{.}06\%$

C$)7\mathrm{.}12\%$

D$)6\mathrm{.}44\%$

E$)8\mathrm{.}33\%$