Following are costs for eight different items. Costs are shown for three different levels of units produced and sold. Classify each of the eight cost items as either variable, fixed, or mixed. Costs for Different Levels of Units Produced and Sold Direct labor At 0 units $ 0 At 2,000 units $ 13,000 At 4,000 units $ 26,000 Depreciation on factory equipment 6,000 6,000 6,000 Direct materials Rent on factory building Salesperson compensation Factory supervisor salary Factory utilities Insurance on factory building 0 9,000 18,000 4,000 4,000 4,000 6,000 6,000 7,000 7,000 7,000 7,000 400 800 1,000 1,550 1,550 1,550 Direct labor Depreciation on factory equipment Direct materials Rent on factory building Salesperson compensation Factory supervisor salary Factory utilities Insurance on factory building