Which packaging innovation, first introduced for military use during WWII, revolutionized food preservation for soldiers and later became ubiquitous in civilian food storage?

Throughout military history, battlefield nutrition has been crucial to maintaining fighting forces. From ancient armies carrying dried meats to modern soldiers with scientifically formulated MREs (Meals, Ready-to-Eat), the packaging and preservation of military rations represents one of the most important but often overlooked innovations in warfare. This trivia question explores how packaging innovations revolutionized military logistics and sustained armies in the field.

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Vacuum-sealed foil pouches
DEHYDI (Dehydrated Individual) ration tins
The SPAM can (Hormel's pressed ham product)
The Retort pouch (flexible packaging that could be heat-sterilized)