The new weapons of world war i, such as tanks, airplanes. flamethrowers, and poison gases, were supposed to

B is actually the only one that makes sense. It was all-out war, they wouldn't be concerned about trimming armies. There was no Geneva convention at the time, and they wouldn't ban new inventions in the middle of a war. And Germany didn't invent all these weapons.

But trench warfare was driving everyone mad with boredom and conditions were terrible. People were willing to try anything to break the stalemate.