Department S had no work in process at the beginning of the period. It added 12,000 units of direct materials during the period at a cost of $84,000; 9,000 units were completed during the period; and 3,000 units were 30% completed as to labor and overhead at the end of the period. All materials are added at the beginning of the process. Direct labor was $49,500 and factory overhead was $9,900. The total cost of units completed during the period was Oa. $121,000 Ob. $127,450 Oc. $143,400 Od. $117,000