18. USA Manufacturing issued 30 -year, 7.5 percent semiannual bonds 6 years ago. The bonds currently sell at 101 percent of face value. What is the firm's after-tax cost of debt if the tax rate is 21 percent? A. 4.82 percent B. 5.85 percent C. 3.76 percent D. 3.59 percent E. 4.40 percent