Which innovation made WWI casualties higher than any other previous war?

A)a new defensive tactic known as trench warfare

Trench warfare allowed the war to drag on for long periods of time because of the stalemates that ensue from the opposing armies refusing to give up the land under their controls, resulting in high casualties in no man's land.

he supported the seperation of church and state. he also promoted religious tolerance.

the exclusive possession or control of the supply or trade in a commodity or service.