Use this information about Department A to answer the question that follow. Department A had 4,600 units in Work in Process that were 62% completed as to labor and overhead at the beginning of the period. 31,500 units of direct materials were added during the period, 33,200 units were completed during the period, and 2,900 units were 21% 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 a. 36,100 b. 28,600 c. 33,200 d. 31,500