Micro Spinoffs, Inc., issued 20-year debt one year ago today at par value with a coupon rate of 9 percent, paid annually. Today, the debt is selling at $1,050. If the firm's tax rate is 34 percent, what is its after-tax cost of debt?

a. 9 percent

b. 8.46 percent

c. 5.94 percent

d. 5.58 percent