XYZ Inc. hired you to help them estimate the cost of equity. The yield on the firm's bonds is 6%, and you believe that the cost of equity can be estimated using a risk premium of 3.45% over a firm's own cost of debt. What is an estimate of the firm's cost of equity?

a. 9.99% b. 12.45% c. 9.45% d. 15.16% e. 10.45%