The market value of XYZ Corporation's common stock is $40 million and the market value of its risk-free debt is $60 million. The beta of the company's common stock is 0.8, and the expected market risk premium is 10%. If the Treasury bill rate is 6%, what is the firm's cost of capital? (Assume no taxes.)

a) 9.2%

b) 8.1%

c) 14.0%

d) 10.8%