Which military packaging innovation from World War II later revolutionized civilian food preservation and is now common in supermarkets worldwide?

Throughout military history, the packaging of combat rations has evolved dramatically to meet the unique challenges of warfare. From Napoleon's preserved food tins to modern MREs (Meals Ready to Eat), packaging innovation has been crucial for military success. This poll tests your knowledge about how military food packaging has evolved and influenced civilian packaging technology. Can you identify which packaging innovation revolutionized both military logistics and later transformed civilian food preservation?

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K-Ration waxed cardboard boxes
Retort pouches (flexible packaging that can be sterilized with contents inside)
P-38 can openers included with C-Rations
Olive drab colored tin cans with key-wind opening mechanisms