Saalfrank Corporation is considering two alternatives that are code-named Mand N. Costs associated with the alternatives are listed below: Supplies costs Assembly costs Power costs Inspection costs Alternative M $61,000 $28,000 $12,000 $21,000 Alternative N $47,000 $28,000 $22,000 $12,000 Required: a. Which costs are relevant and which are not relevant in the choice between these two alternatives? b. What is the differential cost between the two alternatives? a. Supplies costs Assembly costs Power costs Inspection costs b. Differential cost