Answer:
M-A-I-N
Step-by-step explanation:
M: Militarism
The countries developed new and more capable weapons, each competing to outdo one another.
A: Alliances
Alliances formed before WWI include the alliance between Russia, Great Britain and France called the Triple Entente, and the alliance between Austria-Hungary, Italy, and Germany, called the Triple Alliance.
I: Imperialism
When the war began between the Austro-Hungarian Empire and Serbia, colonies recruited their subjects into war, drawing the entire world into war.
N: Nationalism
Nationalism increased the desire for major economic powers to establish themselves as economic and military powers within Europe.