Consider the following data of Department Z: Work in process on January 1, 2020: 800 units - 100% materials, 40% conversion Processed and transferred out: 20,000 units Work in process on January 31, 2020: 1,000 units - 100% materials, 60% conversion Under weighted average method, the equivalent units of production of Department Z for January are: A 21,800 units for materials and 20,920 units for conversion costs B 20,200 units for materials and 20,280 units for conversion costs C) 20,000 units for materials and 20,000 units for conversion costs 21,000 units for materials and 20,600 units for conversion costs