Norris, Inc. is considering two options, P & Q. Costs associated with the options are listed below: Option P Option Q Supplies costs $ 67,000 $ 60,000 Assembly costs $ 41,000 $ 41,000 Power costs $ 21,000 $ 32,000 Inspection costs $ 34,000 $ 23,000 Required: a. Which costs are relevant and which are not relevant in the choice between these two options? b. What is the differential cost between the two options?