Preparation for war through raising troop levels and upping weapon production is an example of militarism.
The statement isn't talking about the causes of raising troop levels and weapon production; if it were, then Nationalism and Imperialism could complete it correctly.
Conscription is but a way to increase troop levels. It is not what the question is looking for.
The question is not looking for causes or for ways a troop can be increased; it wants you to identify what it means to increase troops and to up weapon production. This kind of action strengthens the military and serves to intimidate enemies. That's militarism.