Which of the following statements is CORRECT? a. The WACC as used in capital budgeting is an estimate of a company's before-tax cost of capital. b. The WACC as used in capital budgeting would be simply the before-tax cost of debt if the firm plans to use only debt to finance its capital budget during the coming year. c. There is an "opportunity cost" associated with using retained earnings, hence they are not "free." d. The percentage flotation cost associated with issuing new common equity is typically smaller than the flotation cost for new debt