A firm has $30\%$ debt and $70\%$ equity. The cost of equity is $12\%,$ the before$-$tax cost of debt is $8\%,$ and the tax rate is $34\%.$ The WACC is:

$8\mathrm{.}65\%$

$8\mathrm{.}22\%$

$9\mathrm{.}31\%$

$9\mathrm{.}98\%$