In addition to fighting in the army how did Europeans colonies contribute to the war effort?

The uneven division of the colonies led to war.

Explanation:

The beginning of the 20th century was accompanied by European countries' efforts to acquire as many colonies as possible. France and Great Britain led the way in the colonization of the world. The German Empire and Austro-Hungary wanted a part for themselves. France and Great Britain were not interested in the possible division of the colonies; they were satisfied with the state of dominance in terms of colonization. In such circumstances, nationalism is strengthening on all sides. War rhetoric is being created among those countries, which leads to the strengthening of nationalist propaganda. The uneven division of colonies among European countries was the main factor that led to the First World War. The assassination of Prince Franz Ferdinand in Sarajevo in 1914 was just a pretext for starting the war.

the answer wold be b) travel among nations should be regulated by an international organization