Schedule of Activity Costs Quality Control Activities Activity Cost Process audits $48,900 Training of machine operators 29,300 Processing returned products 18,500 Scrap processing (disposal) 24,500 Rework 8,600 Preventative maintenance 27,200 Product design 45,900 Warranty work 8,400 Finished goods inspection 22,400 From the provided schedule of activity costs, determine the value-added costs. Oa. $182,100 Ob. $173,700 Oc. $233,700 Od. $151,300