Which statement describes an effect of poisonous gas is used in combat during world war l

There was a gas called mustard gas that was primarily used in WW1. After that war, it has been banned for use.

in 550 b.c.e. cyrus the great, the leader of the persians, conquered the medes and united the iranian people under one ruler for the first time. cyrus became the first king of the persian empire and went on to establish one of the largest empires in world.