Schedule of Activity Costs Quality Control Activities Activity Cost Process audits $49,300 Training of machine operators 25,400 Processing returned products 18,100 Scrap processing (disposal) 24,500 Rework 6,300 Preventative maintenance 29,500 Product design 42,200 Warranty work 8,500 Finished goods inspection 23,200 From the provided schedule of activity costs, determine the value-added costs. Oa. $227.000 Ob. $169,600 Oc. $146,400 Od. $178,100