Which packaging innovation was introduced in the K-Ration during WWII that dramatically improved food preservation for soldiers in combat?

During World War II, packaging innovations revolutionized how soldiers were fed in combat zones. The development of specialized combat rations represented a significant advancement in military logistics and soldier readiness. This poll tests your knowledge about one of the most important packaging innovations in military history and how it transformed battlefield nutrition and morale.

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Waxed paperboard boxes that were waterproof and compact
Aluminum cans with pull-tab technology
Glass vacuum jars with rubber seals
Tinfoil packages with heat-resistant liners