Which retail innovation did Clarence Saunders patent in 1917 that fundamentally changed how customers shop in stores?

The world of retail has been revolutionized by numerous inventions and discoveries throughout history. Some innovations completely transformed how products are marketed, displayed, and sold to consumers. Test your knowledge about a groundbreaking retail strategy that changed shopping behavior forever and influenced countless stores worldwide.

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Self-service shopping (Piggly Wiggly's revolutionary model where customers select their own merchandise)
Shopping cart (the wheeled basket that allows customers to collect multiple items)
Barcode scanning (the system for electronically reading product information at checkout)
Department store layout (organizing retail space into specialized sections for different product categories)