What adaptations did the troops make for fighting in the trenches apush?

The correct answer to this open question is the following.

The question is referring to the war in the trenches during World War 1.

The adaptations that the troops made for fighting in the trenches during World War 1, were the following. Soldiers had to modify the strategy when they built the trenches in the war front. The trenches were built to protect soldiers from firearms from the enemy. The strategy used prolonged the war in what historians call "a stalemate in the Western Front," from 1914 to 1918.

the answer is a glaciers carved a large valley that later flooded and became puget sound

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