The correct answer for the question that is being presented above is this one: "mountains." The physical feature that separates various ethnic groups from each other in the Balkans are mountains. They are the ones that show division among the ethnic groups.
Mountains are very prominent in the Balkan region and present a natural impasse for the people due to which they cannot freely traverse from one ethnic group to another (this was so in the past at least, as it has drastically changed since).
