Which of the following accurately explains one of the factors that contributed to World War I?
A. European countries began giving up control of their imperial territory in an effort to spread true democracy.
B. European countries began promoting the idea that citizens should be loyal to large, diverse empires instead of small nations.
C. European countries entered into military alliances that required them to protect one another from attacks.
D. European countries reduced funding for their militaries, making them weak and easy targets for foreign aggression.