Ships could reach the port of st. petersburg via the baltic sea. where is that sea?

Bordered by the coasts of Germany ,Denmark , Poland ,Sweden, Finland,Russia,Estonia ,Latvia among others

The Port of St. Petersburg is a port which can be located near the downtown of St. Petersburg, Florida. The Baltic sea is a sea that can be found in the Atlantic Ocean. 

The sea is then found at the bordered by the coasts of Denmark, Germany, Finland, Sweden, Poland, Russia and etc. 

Since wxyz is 4, halfof that would be 2.

Ithink the answer is either a , c or d