Department S had no work in process at the beginning of the period. 12,000 units of direct materials were added 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 conversion costs for the period were:

a) $59,400

b) $49,500

c) $143,400

d) $9,900