Which packaging innovation was first widely adopted in military PX stores during WWII before becoming a civilian retail standard?

Post-Exchange (PX) and Base Exchange (BX) stores have a fascinating history in military retail. These stores evolved from simple sutlers' tents during the American Civil War to modern retail operations that influence civilian retail practices. This poll tests your knowledge about a significant packaging innovation that originated in military retail and later revolutionized civilian consumer goods packaging worldwide. How well do you know the intersection of military necessity and retail innovation?

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Aerosol spray cans (developed to dispense insecticides for troops in the Pacific)
Vacuum-sealed packaging (originally designed for K-rations)
Aluminum cans (created to reduce shipping weight for overseas deployment)
Blister packaging (developed to protect medical supplies in humid conditions)