Which of the following is NOT a type of storage system commonly used in warehouses?

The choice indicating underwater storage tanks is not a type of storage system commonly used in warehouses because traditional warehousing practices focus on systems designed for dry goods and materials. Pallet racking, shelving, and automated storage and retrieval systems are all well-established methods for organizing and storing inventory efficiently within a warehouse environment.

Pallet racking systems facilitate the storage of goods on pallets, maximizing vertical space and allowing for easy retrieval. Shelving provides a way to store items of varying sizes, making it suitable for smaller products. Automated storage and retrieval systems enhance efficiency through mechanization, allowing for faster access and better space utilization. These methods are specifically designed to cater to the needs of inventory management in warehouses, whereas underwater storage tanks do not align with standard warehousing operations or practices.