WIP Inventory, January 10 unitsUnits started7200Units completed and transferred out3000WIP Inventory, December 314200Direct materials$15,500Direct labor$18,400Manufacturing Overhead$9,000The units in ending WIP Inventory were 90% complete for materials and 85% complete for conversion costs. At the end of the year, what are the equivalent units for conversion costs?

a. 3,000

b. 3,570

c. 6,120

d. 6,570