12. The following is an account for a production department, showing its costs for one month: Goods in Process Inventory 5,400 21,600 Balance Direct materials Direct labor Overhead 16,200 10,800 Assume that materials are added at the beginning of the production process and that direct labor and overhead are applied uniformly. If the units in ending goods in process inventory cost S4,590, and the started and completed units cost $41,850, what was the cost of completing the units in the beginning goods in process inventory? E. $37,260 A. $12,150 B. $ 2,160 D. S54,000 C. $ 7,560