Which military retail innovation, first developed during WWII, revolutionized civilian shopping and is considered the precursor to the modern self-service supermarket?

Throughout history, military supply chains have pioneered retail innovations that later transformed civilian commerce. From the Roman Legion's standardized equipment distribution to modern military PX systems, warfare has driven retail evolution in surprising ways. This poll tests your knowledge of a pivotal retail innovation that emerged from military necessity but changed how we shop forever.

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The military commissary system with its standardized pricing structure
The K-ration packaging design with portion control and long shelf life
Self-service PX (Post Exchange) stores that eliminated clerk-assisted shopping
Military catalog ordering systems with centralized distribution