Which packaging innovation was specifically introduced in the K-Ration design that revolutionized field feeding for WWII soldiers?

In World War II, packaging design became crucial for military logistics. K-Rations were individual daily combat food rations introduced by the United States Army during World War II. Their innovative packaging revolutionized how soldiers received nutrition in the field. Test your knowledge about this groundbreaking military consumer product that influenced modern emergency food packaging and MREs (Meals, Ready-to-Eat).

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Waterproof waxed cardboard boxes that could float and be used as emergency flotation devices
Individual moisture-resistant cellophane wrappers for each food component, preventing spoilage
Self-heating containers using chemical reactions to warm food without fire
Biodegradable packaging made from compressed rice paper that could be consumed with the rations