Niles is writing a report on the

For Niles's report on the events that led to the outbreak of World War II, the best structure to use would be cause-effect. This structure allows him to discuss the various factors and events that contributed to the war's outbreak, demonstrating how specific causes directly led to the conflict. By focusing on cause and effect, he can clearly illustrate the relationships between different historical events and the eventual consequences that resulted in World War II.