Aaron corporation, which has only one product, has provided the following data concerning its most recent month of operations: selling price $ 90 units in beginning inventory 0 units produced 3,400 units sold 3,000 units in ending inventory 400 variable costs per unit: direct materials $ 21 direct labor $ 38 variable manufacturing overhead $ 6 variable selling and administrative expense $ 4 fixed costs: fixed manufacturing overhead $ 54,400 fixed selling and administrative expense $ 3,000 what is the unit product cost for the month under variable costing?
a. $69 per unit
b. $65 per unit
c. $85 per unit
d. $81 per unit