Which of these statements is true for a firm that produced and sold 600 units during its first month of business? A. Its operating income for the month will be lower under variable costing than under absorption costing. B. Its operating income for the month will be higher under variable costing than under absorption costing. OC. The value of its ending finished goods inventory on the balance sheet will be higher under variable costing than under absorption costing. D. Its operating income will be the same under variable costing as under absorption costing