Department A had 4,800 units in work in process that were 77% completed as to labor and overhead at the beginning of the period, 31,900 units of direct materials were added during the period, 34,300 units were completed during the period; and 2,400 units were 25% completed as to labor and overhead at the end of the period. All materials are added at the beginning of the process. The first-in, first-out method is used to cost inventories. The number of equivalent units of production for material costs for the period was Oa. 36,700 Ob. 31,900 Oc. 34,300 Od. 29,500