Selected costs related to Apple's iPhone are listed below. Identify each cost as either direct materials, direct labor, factory overhead, selling expenses, or general and administrative expenses by selecting the appropriate dropdowns. 1. Camera 2. Advertising campaigns 3. Maintenance of assembly equipment 4. Depreciation on office equipment 5. Depreciation (straight-line) on robotic equipment used in assembly 6. Salary of the chief executive officer 7. Assembly-line supervisor salary 8. Wages for retail store worker