20. A firm's bonds have a maturity of 12 years with a $1,000 face value, have an 8% semiannual coupon, are callable in 6 years at $1,068.66, and currently sell at a price of $1,128.13. What is their nominal yield to call? a. 8.44% d. 7.72% b. 6.36% e. 9.09% c. 7.90%