The market value of GM' common stock, preferred stock and debt are $8 billion, $4 billion and $12 billion respectively. GM has a beta of 1.3, the market risk premium is 7% and the risk-free rate of interest is 4%. GM's preferred stock pays a dividend of $4 each year and trades at a price of $30 per share. GM's debt trades with a yield to maturity of 8.5%. What is GM's weighted average cost of capital if its tax rate is 30%?

A. 8.01%

B. 8.34%

C. 9.56%