Which packaging innovation, developed during World War II, revolutionized military field rations and later became widely adopted in civilian food preservation?

Throughout military history, packaging innovations have played a crucial role in preserving supplies and equipment for troops in the field. From ancient methods of preserving rations to modern tactical packaging designed for extreme environments, these innovations have directly impacted military effectiveness and sometimes changed the course of conflicts. Test your knowledge about a revolutionary packaging development that transformed military logistics during a pivotal historical period.

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The K-Ration's waxed cardboard boxes with moisture-resistant cellophane inner wrapping
MRES (Meals Ready to Eat) in retort pouches
The SPAM tin with key-wind opening mechanism
The Subsistence Research Laboratory's development of PVDC (Saran) food wrap