Assume that you are on the financial staff of Bertin Corporation, and you have collected the following data: $(1)$ The yield to maturity on the company's outstanding $8\%$ annual coupon bonds is $7\%,$ and its tax rate is $25\%.(2)$ The risk$-$free rate is $4\mathrm{.}0\%,$ the market risk premium $($rM $-$ TRF$)$ is $6\mathrm{.}0\%,$ and the firm's beta is $0\mathrm{.}90.$

$(3)$ The firm's capital structure consists of $35\%$ debt and $65\%$ equity. What is Bertin's WACC?

$7\mathrm{.}21\%$

$7\mathrm{.}50\%$

$7\mathrm{.}95\%$

$8\mathrm{.}21\%$

$8\mathrm{.}56\%$