Schedule of Activity Costs Quality Control Activities Activity Cost Process audits $50,000 Training of machine operators 28,000 Processing returned products 19,000 Scrap processing (disposal) 25,000 Rework 8,000 Preventive maintenance 30,000 Product design 46,000 Warranty work 12,000 Finished goods inspection 23,000 From the provided schedule of activity costs, determine the value-added costs. Oa. $177,000 Ob. $156,000 Oc. $191,000 Od $104,000