During World War II, which packaging innovation was specifically developed for U.S. troops that revolutionized combat rations and later influenced civilian food packaging?

Throughout military history, the packaging of combat rations has evolved dramatically to meet the needs of soldiers in various combat environments. From tinned foods in the Napoleonic era to modern MREs (Meals, Ready-to-Eat), packaging technology has been crucial for troop sustainment. This trivia focuses on a significant packaging innovation that revolutionized battlefield nutrition during one of history's major conflicts.

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The K-Ration's waxed cardboard boxes with moisture-resistant coating
The P-38 can opener with folding metal design
Glass vacuum jars with rubber sealing gaskets
Aluminum foil pouches with heat-sealed edges