Which of the following is NOT an appropriate control over inventory? 1. Use of pre-numbered requisitions, purchase orders, and receiving reports. O2. Segregation of duties over authorization of purchases and custody of inventory. O3, Periodic changes in cost flow assumption (e.g. FIFO). 4. Limited access to inventories. Which of the following is NOT an appropriate control over inventory? 1. Use of pre-numbered requisitions, purchase orders, and receiving reports. O2. Segregation of duties over authorization of purchases and custody of inventory. O3, Periodic changes in cost flow assumption (e.g. FIFO). 4. Limited access to inventories.