Cost of debt. Dunder$-$Mifflin, Inc. $($DMI$)$ is selling $600,000$ bonds to raise money for the publication of new magazines in the coming year. The bond will pay a coupon rate of $15\mathrm{.}1\%$ with semiannual payments and will mature in $30$ years. Its par value is $$100.$ What is the cost of debt to DMI if the bonds raise the following amounts $($ignoring issuing costs$)?$

a$.$ $$58,806,000$

b$.$ $$57,192,000$

c$.$ $$64,230,000$

d$.$ $$73,164,000$