A company is determining the cost of debt to use in its weighted average cost of capital. It has recently issued a 10-year, 6 percent semiannual coupon bond for $ 864. The bond has a maturity value of $1 000. If the marginal tax rate is 35 percent, the cost of debt they should use in their calculation is closest to:（）
A. 4.3%.
B. 5.2%.
C. 6.1%.
