Answer:
dark, negative, gloomy and other synonyms is what i think made the world war 1 poster effective.
Explanation:
i say this because the poster gave the people/citizens something in common to worry about, death and horror. this imagery probably made other posters least effective because some people don't like to see and/or experience death, horror, and negativity so they keep their heads up and ignore it.
hope this helps, also plz mark brainliest
