Use this information about Department A to answer the question that follow. Department A had 4,200 units in Work in Process that were 67% completed as to labor and overhead at the beginning of the period. 29,400 units of direct materials were added during the period, 31,300 units were completed during the period, and 2,300 units were 36% 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. 31,300 Ob. 29,400 Oc. 33,600 Od. 27,100