Suppose that a company has a $10\mathrm{.}0\%$ cost of debt and the corporate tax rate is $34\%,$ what is its after$-$tax cost of debt?

$3\mathrm{.}4\%$

$5\mathrm{.}2\%$

ViII

$10\mathrm{.}0\%$

$6\mathrm{.}6\%$