One would be nationalism because it forced all nation states to integrate together and become one same culture and religion ,knowing that not all people have the same religion it would disrespectful to that state and imperialism because It made Europeans seek for land to make more empires and establishes territories such as Asia and Africa .Cause conflict between these multiple areas
The answer to this question is:
Atomic Bomb
World War also started after archduke Francis Ferdinand got assassinated.
To protect people from national government
