Which of these military product innovations was first mass-produced and deployed during World War I, fundamentally changing battlefield mobility and tactics?

Throughout military history, certain product innovations have dramatically transformed battlefield tactics and strategy. The early 20th century saw particularly rapid development of new military technologies that would forever change how wars were fought. This trivia question focuses on a pivotal product development that reshaped modern warfare and influenced military doctrine for decades to come. Test your knowledge of how industrial innovation intersected with military needs to create a revolutionary combat platform.

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The combat tank (first deployed by Britain as the Mark I in 1916)
The military helicopter (first deployed as the Focke-Wulf Fw 61 in 1936)
The aircraft carrier (first purpose-built carrier HMS Hermes commissioned in 1924)
The self-propelled artillery (first mass deployment of the Sturmpanzerwagen A7V in 1918)