WWI was caused by many things, among them was the assassination of Franz Ferdinand leading to the Austria-Hungary empire declaring war on Serbia which dragged most of Europe into the war due to alliances. The U.S. entered the war due to Germanys war tactics and the Zimmermann note.
It left fewer british troops to fight in north america
Answer:
American Americans were allowed to join armed forces
they thought if one country in an area fell to communism the countries surrounding the country would also fall to communism which lead to the red scare.
Answer: B Catholicism and Judaism
Explanation: those are the most common religions in Europe