Estimate unit variable costs and total fixed costs using the following data. The data represents total costs incurred in July. The firm produced 10 units in July. rent $200 direct materials + direct labor $100 fire insurance $50 sales commissions (5% of revenue) $20 A. unit variable cost = $120/unit, fixed cost=$250 B. unit variable cost = $12/unit, fixed cost=$250 C. unit variable cost = $15/unit, fixed cost=$220 D. unit variable cost = $10/unit, fixed cost=$270