Answer:
Following were the underlying causes of WW1:
1. Militarism
2. colonialism
3. Group formation
4. Assassination of Archduke
Step-by-step explanation:
Militarism was at peak during early 1900s which caused aggression and competition between different countries.
Almost entire Europe had built their empire in parts of Asia, Africa and struggles and fight for the colonialism was also a reason for the war.
There was a Group formation among countries in Europe. France, Britain and Russia at one side and Germany, Austria and Italy at other side.
Another important reasoned which invoked the war was Assassination of Archduke who was the heir of Hungary Throne by Serbia. This served as an immediate cause because Austria-Hungary declared war on Serbia