Mark the correct statements.

a) The water of the Baltic sea has a salty taste.
b) Herring and tuna are some of the most common fish species of the Baltic Sea.

c) The Baltic Sea often freezes completely during the winter.
d) Tallinn and St. Petersburg are located on the shores of the Baltic Sea.

e) Oil tanker traffic is one of the most significant threats to the nature of the Baltic Sea.
f) The Baltic Sea receives no water from the Atlantic Ocean.
g) Åland, Hiiumaa and Gotland are all islands in the Baltic Sea.