Which of these common retail technologies was originally developed for military use during World War II?

Many military technologies have found their way into civilian retail products we use every day. These innovations often began as military developments before being adapted for commercial use. Test your knowledge about how warfare has unexpectedly shaped the products on store shelves and the way we shop in the modern world.

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RFID tracking technology (used in inventory management)
Barcode scanners (used at checkout counters)
Digital price displays (used on store shelves)
Self-checkout kiosks (used in modern supermarkets)