Doon Company incurred the following costs while producing 400 units: direct materials, $8 per unit; direct labor, $30 per unit; variable manufacturing overhead, $12 per unit; total fixed manufacturing overhead costs, $4,000; variable selling and administrative costs, $3 per unit; total fixed selling and administrative costs, $3,200. There are no beginning inventories. What is the operating income using variable costing if 360 units are sold for $180 each? A. $38,520 B. $38,920 C. $45,720 D. $39,600