The use of trench warfare had which of these effects on world war i? a) it made conquering new territory difficult for opposing armies. b) it made navel power more important than in previous wars. c) it reduced the effectiveness of poison gas and machine guns. d) it led to a significant decline in the death rate among soldiers.

The correct answer is A) It made conquering new territory difficult for opposing armies.

There was no way to go across fields since any leaving the trenches would be punished by opponents who were in other trenches. Nerve gas and biochemical weapons were extremely successful because they would be thrown into the opposing trenches and would kill opponents.