The corporate tax rate is $21\%.$ ABC Corporation is financed with $$150$ million of bonds with an interest rate of $10\%,$ and with $$450$ million of common stock having a required return of $18\%.$ This company's Weighted Average Cost of Capital $($WACC$)$ is $\_\_\_\_\_\_.$

$11\mathrm{.}25\%$

$15\mathrm{.}48\%$

$9\mathrm{.}25\%$

$10\mathrm{.}38\%$

$13\mathrm{.}23\%$