11. Data: A company operates a process costing system using the FIFO method of valuation. All materials are input at the commencement of the process. Conversion costs are incurred evenly throughout the process. The following data relates to last period: Opening work in progress: 2,000 units, 60% completed Total number of units completed: 14,000 units Closing work in progress: 3,000 units, 30% completed Material costs: 51,000 Conversion costs: 193,170 Question: What was the total number of units input during last period? A) 12,000 B) 13,000 C) 15,000 D) 17,000