Metropole Skating produces 1,000 skates during the month. It's variable costs are $3.00 per unit for direct materials, $5 per unit for direct labor, $3.00 per unit for variable overhead, and $1 per unit for variable selling and administrative expenses. Metropole's fixed overhead is $3,000 total, and its fixed selling and administrative expenses total $1,000. Metropole's cost per unit under variable costing is: a. $11 per unit b. $12 per unit. C. $15 per unit. d. $16 per unit