Schedule of Activity Costs Quality Control Activities Activity Cost Process audits $50,200 Training of machine operators 27,400 Processing returned products 16,800 Scrap processing (disposal) 26,800 Rework 7,400 Preventative maintenance 27,800 Product design 45,100 Warranty work 8,300 Finished goods inspection 22,600 From the provided schedule of activity costs, determine the external failure costs. Oa. $86,700 Ob. $59,300 Oc. $25,100 Od. $20,080