The correct answer is C) New boundaries caused Hungary to lose most of its population.
European nations were affected by the five treaties established at the end of the war in that new boundaries caused Hungary to lose most of its population.
We are referring to the treaties after World War 1. After this destructive period of armed confrontation, nations had to sign treaties to formally establish peace in Europe and modify the territories.
Specifically, the treaties of Lausanne, Trianon, and Sevres, established that Hungary was going to be an independent state. By signing the treaty of Trianon of November 1920, Transylvania was no more a Hungary territory. It was passed to Romania. Slovakia was ceded to Czechoslovakia, and other portions of Hungary were ceded to Yugoslavia.
