Department R had 4,700 units in work in process that were 64% completed as to labor and overhead at the beginning of the period. During the period, 29,000 units of direct materials were added, 31,500 units were completed, and 2,200 units were 33% 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

a.31,500

b.33,918

c.38,400

d.29,218