Detailed Instructions: You are given a concept, and a list of answers. You should generate a question about the concept that leads to the given answer(s).
Q: concept: Baltic Sea answers: ['Atlantic Ocean', 'East Prussia', 'Pomeranian Voivodeship - II RP', 'Free City of Danzig', 'Second Polish Republic', 'North German Plain']
A:
which countries border the baltic sea?