Department B had a beginning inventory of 4000 units, 1/4 completed; an ending inventory of 3900 units, 2/3 completed, and received 2100 units during the period from Department A. What were the equivalent units of production of Department B, assuming weighted-average process costing?

A) 3200 equivalent units.
B) 4800 equivalent units.
C) 3300 equivalent units.
D) 4700 equivalent units.