The debits to Work in Process--Assembly Department for April, together with data concerning production, are as follows: April 1, work in process: Materials cost, 3,000 units $ 7,500 Conversion costs, 3,000 units, 80% completed 6,000 Materials added during April, 10,000 units 29,000 Conversion costs during April 35,000 Goods finished during April, 11,500 units --- April 30 work in process, 1,500 units, 60% completed --- All direct materials are placed in process at the beginning of the process and the average cost method is used to cost inventories. The materials cost per equivalent unit (to the nearest cent) for April is: a. $3.02 b. $2.81 c. $2.26 d. $2.60