What were the four types of trenches used by the allies

There was the front line trench (allies would attack from there), the support trench (housed reinforcements and supplies behind the front line trench), the reserve trench (they had more supplies and men ready to fight should the first two trenches be attacked and overrun by the enemy), and the communication trench (transported messages, soldiers, and supplies to the other trenches).

C. the delegated powers