Stryker Industries received an offer from an exporter for 27,000 units of product at $18 per unit. The acceptance of the offer will not affect normal production or domestic sales prices. The following data is available: Domestic unit sales price $24 Unit manufacturing costs: Variable 12 Fixed 6 What is the differential cost from the acceptance of the offer? a.$162,000 b.$648,000 c.$324,000 d.$486,000