Which design innovation was specifically incorporated into the US Army's Advanced Combat Helmet (ACH) based on research into how soldiers actually use their equipment in combat zones?

Combat helmets have undergone significant design evolution throughout military history. From ancient bronze helmets to modern ballistic protection systems, each design innovation reflects both technological capabilities and understanding of battlefield injuries. This poll tests your knowledge of a pivotal product design decision that changed modern military helmet development following extensive combat psychology research and injury analysis.

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Increased top padding to protect against IED blasts from below
Extended ear coverage that allows compatibility with communications equipment
Lighter weight materials sacrificing protection for increased mobility
Integrated night vision mounting system eliminating separate attachments