Question

around 1900, european nations built up their military forces, formed alliances, and expanded their colonial holdings in their efforts to
force their enemies to start wars.
maintain a balance of power.
put a conscription system in place.
end the spirit of militarism.

Explanation:

In the late 19th - early 20th century, European powers were engaged in a complex geopolitical situation. Building up military forces, forming alliances (like the Triple Entente and Triple Alliance), and expanding colonial holdings were strategies to ensure that no single power became too dominant. The balance - of - power theory posits that states (or groups of states) act to prevent any one state from gaining enough power to dominate others. Military build - ups were a means of self - defense and a way to project power. Alliances were formed to counterbalance the power of rival alliances. Colonial expansion provided resources and strategic locations, which also contributed to a nation's overall power.
Forcing enemies to start wars was not the main goal; rather, these actions were more about deterrence and maintaining a stable (relative) power structure. A conscription system (a method of enlisting soldiers) was a part of military build - up but not the overarching reason for the combination of military build - up, alliances, and colonial expansion. Militarism (a belief in the importance of military power) was actually promoted by these actions, not ended.

Answer:

maintain a balance of power.