Department R had 4,000 units in work in process that were 66% completed as to labor and overhead at the beginning of the period. During the period, 27,300 units of direct materials were added, 28,500 units were completed, and 2,800 units were 39% 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 conversion costs for the period was Oa. 26,952 Ob. 30,952 Oc. 35,300 Od. 28.300