Galvatron Metals has a bond outstanding with a coupon rate of $6\mathrm{.}4$ percent and semiannual payments. The bond currently sells for $$1,912$ and matures in $16$ years. The par value is $$2,000$ and the company's tax rate is $21$ percent. What is the company's aftertax cost of debt?

Multiple Choice

$3\mathrm{.}43\%$

$4\mathrm{.}11\%$

$5\mathrm{.}42\%$

$4\mathrm{.}72\%$