Which transportation innovation was specifically developed by Amazon to solve the 'last-mile delivery' challenge in retail inventory management?

The transportation industry has dramatically changed how retailers handle inventory management and customer experience. From air freight revolutionizing global supply chains to ride-sharing services affecting urban retail, transportation innovations continue to reshape retail operations. Test your knowledge about how transportation and retail inventory management intersect in this challenging trivia question!

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Amazon Prime Air (drone delivery service)
Amazon Relay (trucking app for freight partners)
Amazon Flex (gig economy delivery program)
Amazon LineHaul (long-distance freight network)