Department A had 4,500 units in Work in Process that were 75% completed at the beginning of the period at a cost of $6,400. During the period, 33,900 units of direct materials were added at a cost of $77,970, and 35,600 units were completed. At the end of the period, 2,800 units were 37% completed. All materials are added at the beginning of the process. Direct labor was $27,700 and factory overhead was $5,400. The cost of the 2,800 units in process at the end of the period if the first-in, first- out method is used to cost inventories was Oa. $7,471 Ob. $6,956 Oc. $8,502 Od. $6,440