A corporation is redesigning its warehouse and has decided to use a rack system that allows each level to be accessed individually by placing pallets on wheeled frames. The rack system that best meets this criteria is:

A push-back rack system uses wheeled carts that run on inclined rails within the rack structure. When a pallet is loaded from the aisle, it pushes the pallet already on the cart one position deeper into the rack. This design matches the description of placing pallets on "wheeled frames." It offers higher storage density than selective racking while still allowing access to each level (or lane) individually from the aisle.

A. flow-through: This system uses gravity rollers, not wheeled frames or carts, to move pallets from a loading aisle to a picking aisle (FIFO).
C. drive-in: This system allows forklifts to enter the rack structure to store pallets. It does not use wheeled frames and offers poor selectivity (LIFO).
D. double-deep: This is a static rack system that stores pallets two deep. It requires a special reach truck and does not involve wheeled frames.

1. APICS CLTD Learning System, Module 3, Section A, Chapter 3, "Storage and Handling Equipment." This section details various racking systems, describing push-back racks as using a system of nested carts on rails.

2. Richards, G. (2017). Warehouse Management: A Complete Guide to Improving Efficiency and Minimizing Costs in the Modern Warehouse (3rd ed.). Kogan Page. Chapter 6, "Warehouse Equipment and Systems," describes push-back racking with carts that are pushed back by subsequent pallet loads.