Dunkin Industries sold a 15 year $1,000 face value bond with a 10.5 percent coupon rate. Interest is paid annually. After flotation costs, Dunkin received $920 per bond. Compute the after-tax cost of debt for these bonds if the firm's marginal tax rate is 40 percent.
A. 5.49%
B. 6.99%
C. 8.39%
D. 11.65%