Bulgaria is the term that best fits the definition provided.
Bulgaria is a sovereign member state of the European Union that is located in the southeast of the European continent, its territorial limits are:
According to the above, it can be inferred that Bulgaria is an appropriate term that corresponds to the definition of neighbor to the north of Greece, since it is a country that lies to the north of Greece, so it could be classified as a neighbor.
Other countries that can be classified as neighbors to the north of Greece are:
Note: This question is incomplete because the options are missing. However I can answer it based on my prior knowledge.
Learn more about Greece in: https://brainly.com/question/3671178