Quinlan Enterprises stock trades for $$52\mathrm{.}50$ per share. It is expected to pay a $$2\mathrm{.}50$ dividend at year end $($D $1=$ $$2\mathrm{.}50),$ and the dividend is expected to grow at a constant rate of $5\mathrm{.}50\%$ a year. The before$-$tax cost of debt is $8\mathrm{.}50\%,$ and the copotate tax rate is $40\%.$ The target capital structure consists of $40\%$ debt and $60\%$ common equity. What is the company's WACC if all the equity used is from retained earnings? a$\mathrm{.}8\mathrm{.}20\%$ b$7\mathrm{.}36\%$ c$\mathrm{.}8\mathrm{.}29\%$ d$\mathrm{.}7\mathrm{.}07\%$ e$\mathrm{.}8\mathrm{.}00\%$