A firm has a cost of equity of 13 percent, a cost of preferred of 11 percent, an aftertax cost of debt of 5.2 percent, and a tax rate of 35 percent. Given this, which one of the following will increase the firm's weighted average cost of capital?
a) Increasing the firm's tax rate
b) Issuing new bonds at par
c) Increasing the debt-equity ratio
d) Redeeming shares of common stock
e) Increasing the firm's beta