Yellow Submarine, Co$.$ has a cost of equity of $10\mathrm{.}81$ percent, a cost of debt of $5\mathrm{.}45$ percent, and a tax rate of $21$ percent. The company uses only debt and equity and the company's percentage of debt in its capital structure is $37\%.$ What is the company's WACC?

Multiple Choice

$8\mathrm{.}40\%$

$8\mathrm{.}83\%$

$6\mathrm{.}78\%$

$10\mathrm{.}43\%$