Springer Products manufactures three different product lines, Model X, Model Y, and Model Z. Considerable market demand exists for all models. The following per unit data apply: Model X Model Y Model Z Selling price $56 $67 $76 Direct materials 7 7 7 Direct labor ($12 per hour) 12 12 24 Variable support costs ($6 per machine - hour) 6 12 12 14 14 14 Fixed support costs Which model has the greatest contribution margin per machine - hour? A. Model X B. Model Y C. Model Z D. Both Model X and Model Y have the highest and same contribution margin per machine - hour