Department M had 600 units 60% completed in process at the beginning of June, 6,000 units completed during June, and 700 units 30% completed at the end of June. Using the first-in, first-out method of inventory costing, what was the number of equivalent units of production for conversion costs for the period?
a. 7,300 units
b. 5,640 units
c. 6,700 units
d. 5,850 units