castro chemical company sold a noncallable bond several years ago that now has 20 years to maturity. this bond has a 9% annual coupon, paid semiannually, sells at a price of %1025, and has a par value of $1000. if the firms tax rate is 40%, what is the component cost of debt for use in the wacc calculation?

a. 4.37%

b. 5.24%

c. 5.39%

d.6.09%