Which of the following statements about weighted average cost of capital (WACC) is correct? WACC should use the average cost of debt for all forms as the cost of debt for each individual firm WACC should use the coupon rate on a firm's bonds as the cost of debt WACC should decrease as a firm uses more debt due to the tax deductibility of interest payments WACC should increase as a firm uses more debt due to the tax deductibility of interest payments