A firm issues a $20-$year semi$-$annual coupon payment bond, which nets it $$1,113\mathrm{.}55.$ The coupon rate of the bond is $9\mathrm{.}00\%.$ The tax rate is $21\%.$ What is the after$-$tax cost of debt?

A$.$

$8\mathrm{.}99\%$

B$.$

$7\mathrm{.}91\%$

C$.$

$6\mathrm{.}99\%$

D$.$

$6\mathrm{.}21\%$

E$.$

$5\mathrm{.}53\%$

F$.$

$4\mathrm{.}93\%$

G$.$

$4\mathrm{.}38\%$

H$.$

$3\mathrm{.}90\%$