Which of the following is an example of waste?

Storing extra items in a warehouse is indeed an example of waste in the context of the Lean methodology, which focuses on eliminating non-value-added activities. This practice ties up resources, including space and capital, without contributing to the customer's experience or the efficiency of the process. Excess inventory can lead to additional costs associated with storage and may also result in obsolescence or spoilage if the items are not used in a timely manner.

In contrast, properly training operators, packaging products for shipment, and handling customer orders represent activities that add value to the overall process. Training ensures that employees are skilled and can operate efficiently, properly packaging ensures that products are delivered safely to customers, and handling customer orders is essential for meeting customer needs and ensuring satisfaction. These activities are integral to maintaining a productive and efficient operation, which is why they do not categorize as waste.