Synergy Inc. manufactured 6,000 units during the month of March. It incurred direct materials cost of $120,000 and manufacturing overhead costs of $48,000. If its per-unit prime cost was $31.20 per unit, how much direct labor cost did it incur during March? Oa. $67,200 Ob. $35,000 Oc. $90,000 Od. $20,000