A firm has a cost of equity of 16 percent and an after-tax cost of debt of 7.5 percent. Given this, which one of the following will increase the firm's weighted average cost of capital? Issuing new bonds at par thus adding debt to the firm's capital structure O Increasing the debt-equity ratio Increasing the firm's beta O Buying back shares of common stock, which will increase the price of the stock O Increasing the firm's tax rate