Department R had 4,400 units in work in process that were 80% completed as to labor and overhead at the beginning of the period; 38,000 units of direct materials were added during the period; 40,300 units were completed during the period; and 2,100 units were 30% 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. 37,410

b. 46,800

c. 40,300

d. 41,810