Department A had 4,100 units in work in process that were 69% completed as to labor and overhead at the beginning of the period, 27,100 units of direct materials were added during the period, 28,300 units were completed during the period; and 2,900 units were 37% 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. 24:200 Ob. 31.200 Oc. 27,100 Od. 28.300