The 1 of 4 choice is reasonable.
World Religions
Race, Ethnicity and Nations
Society and Culture
All these are very relevant in re the causes and circumstances of war.
Of the first group.
Social Inequality is much like the above, potentially relevant and useful on the face of it. It’s a long running theme in European History, from the Brothers Gracchi @100BC to current US politics.
It all depends, of course, on HOW they are taught.
A couple of years ago, a WP graduate celebrated Communism for the cameras!