Schedule of Activity Costs Quallty Control Activities Activity Cost Process audits $48,900 Training of machine operators 26,300 Processing returned products 19,500 Scrap processing (disposal) 25,800 Rework 7,800 Preventative maintenance 28,300 41,800 Product design Warranty work 6,900 Finished goods inspection 22,600 From the provided schedule of activity costs, determine the external failure costs. a. $60,000 b. $26,400 c. $86,300 d. $21,120