Zephyr Industries manufactures leaf blowers. Zephyr manufactured 2,000 blowers in October and 2,600 blowers in November. Here are data regarding Zephyr's manufacturing costs: Manufacturing cost 1. Nylon mesh (raw material) 2. Energy used to run machinery and equipment 3. Wages of factory workers, including supervisors 4. Motors purchased from suppliers (component parts) October $120,000 $250,000 $620,000 $480,000 November $156,000 $290,000 $773,000 $624,000 Which costs are properly classified as mixed costs? Only 1 Only 1 and 4 Only 2 and 3 Only 3 and 4 Only 4