Huffer Company uses the weighted-average method in its process costing system. The following information pertains to Processing Department D for the month of May: Number Cost of materials of units Beginning work in process 30,000 $11,000 Started in May 80,000 $36,000 Units completed. 85,000 Ending work in process 25,000 All materials are added at the beginning of the process. The cost per equivalent unit for materials is closest to: a. $0.43. b. $0.45. c. $0.55. d. $0.59.