The correct answer is: Serbs would not have tried to eliminate other groups.
In the 20th century, Yugoslavia was a country that hosted many different ethnic groups, of which the Serbs were the largest one. For this reason, and in general terms, political power was in the hands of Serbs, who used it to try to eliminate the other groups who were seen in the eyes of Serbian people as second-class citizens. This can be seen in the war of the Balkans during the 1990s in the aftermath of the fall of Communism when the Serbian nationalist Slobodan Milosevic committed the crime of genocide against Bosnian people.
If the demographic distribution among ethnic groups would have been similar, perhaps the most likely result would have been that the Serbs would not have tried to eliminate the other groups.