Which military product innovation was initially rejected by leadership but, after successful field demonstrations by its inventor, revolutionized infantry tactics during World War I?

Throughout military history, certain product innovations have dramatically transformed battlefield tactics and strategy. These innovations often began as experimental prototypes before becoming standard equipment. This poll tests your knowledge about how product innovation in military technology influenced major conflicts and shaped the development of modern armed forces. See if you can identify the correct timeline and impact of this revolutionary military product development.

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The Thompson submachine gun, demonstrated by John T. Thompson by shooting through car doors to prove its effectiveness
The portable flamethrower (Flammenwerfer), initially considered too unreliable until Richard Fiedler's improved demonstration in 1915
The Brodie helmet, rejected as unnecessary until Sir John Brodie wore one during an artillery barrage to prove its value
The Lewis gun, initially dismissed by US Army Ordnance, until Isaac Lewis personally demonstrated its reliability in Belgium