The baltic nations are
belarus
estonia
latvia
lithuania
serbia

The Baltic Nations are called so after the Baltic Sea - and they lie on the shore of Baltic Sea. Of the mentioned countries only Lithuania, Latvia and Estonia lie on the Baltic Sea- and they are the correct answer.

In fact, even though other countries lie on the Baltic too, only those three are called "the Baltic countries"

Because broadest terms allows the law flexibility depending on changing society and circumstances.