(TCO 2) The Finishing Department had 5,000 incomplete units in its beginning Work-in-Process Inventory, which were 100% complete as to materials and 30% complete as to conversion costs. 15,000 units were received from the previous department. The ending Work-in-Process Inventory consisted of 2,000 units, which were 50% complete as to materials and 30% complete as to conversion costs. The Finishing Department uses first-in, first-out (FIFO) process costing. How many units were started and completed during the period?

A.12,000

B.13,000

C.18,000

D.20,000