Which statement is true regarding WACC and its components?
a. The WACC may decrease if the firm uses less debt capital and more equity capital.
b. The WACC should be used as the discount rate for all projects that the firm considers.
c. The cost of debt of a firm is usually less than the cost of equity of the firm.
d. For an all-equity firm, the cost of equity of the firm is greater than the WACC of the firm.