Tony is estimating the after$-$tax cost of debt for Gloria Mundi Enterprises. Given the following data, what is Gloria Mundi's cost of debt if its $5-$year bonds are rated BBB and the tax rate is $20\%?$

a$.$

$3\mathrm{.}95\%$

b$.$

$3\mathrm{.}75\%$

c$.$

$3\mathrm{.}85\%$

d$.$

$3\mathrm{.}80\%$

e$.$

$3\mathrm{.}90\%$