You were hired as a consultant to Giambono Company, whose target capital structure is $45\%$ debt, $15\%$ preferred, and $40\%$ common equity. The after$-$tax cost of debt is $6\mathrm{.}00\%,$ the cost of preferred is $8\mathrm{.}00\%,$ and the cost of retained earnings is $14\mathrm{.}00\%.$ The firm will not be issuing any new stock. What is its WACC?

a$.9\mathrm{.}50\%$

b$.6\mathrm{.}80\%$

c$.8\mathrm{.}30\%$

d$.3\mathrm{.}90\%$

e$.9\mathrm{.}33\%$