A firm recently issued $1,000 par value, 15-year bonds with a coupon rate of 8%. Coupon interest payments will be paid semi-annually. The bonds sold at par value, but the firm paid flotation costs amounting to 5% of par value. The firm has a marginal tax rate of 34%. What is the firm's after-tax cost of debt for these bonds? O 8.60% O 6.36% O 5.68% O 4.30% 8.0%