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 $ 7,871 Conversion costs, 3,000 units, 40% completed 5,208 Materials added during April 10,000 units 25,937 Conversion costs during April 32,618 Goods finished during April, 12,000 units 0 April 30 work in process, 1,000 units, 40% completed 0 All direct materials are added at the beginning of the process, and the first-in, first-out method is used to cost inventories. The conversion cost per equivalent unit for April is Oa. $3.26 Ob. $2.51 Oc. $2.84 Od. $2.91