Introduction:
The question asks which one among the given options is not a Baltic nation. The options provided are Latvia, Slovakia, Lithuania, and Estonia. We need to identify the option that does not belong to the Baltic region.

Explanation:
Baltic Nations:
The Baltic region is located in Northern Europe and is composed of three countries known as the Baltic states. These countries are Latvia, Lithuania, and Estonia. These nations have historical, cultural, and geopolitical ties. They share a common coastline along the Baltic Sea and have similar languages and cultural traditions.

Option 'B': Slovakia
Slovakia is not a Baltic nation. It is a landlocked country in Central Europe. It shares borders with Poland, Ukraine, Hungary, Czech Republic, and Austria. Slovakia is known for its beautiful landscapes, castles, and medieval towns. However, it is not part of the Baltic region.

Option 'A': Latvia
Latvia is one of the Baltic nations and a member of the European Union. It is situated in the Baltic region and shares borders with Estonia, Lithuania, Russia, and Belarus. Latvia has a rich cultural heritage and is known for its beautiful capital city, Riga.

Option 'C': Lithuania
Lithuania is another Baltic nation and member of the European Union. It is located in the Baltic region and shares borders with Latvia, Belarus, Poland, and Russia's Kaliningrad Oblast. Lithuania has a long history and is known for its preserved medieval architecture and beautiful landscapes.

Option 'D': Estonia
Estonia is the third Baltic nation and a member of the European Union. It is situated in the Baltic region and shares borders with Latvia, Russia, and the Gulf of Finland. Estonia is known for its technology advancements, beautiful nature, and medieval architecture.

Conclusion:
Among the given options, Slovakia is not a Baltic nation. The Baltic nations are Latvia, Lithuania, and Estonia, which share historical, cultural, and geographical ties. Slovakia, on the other hand, is a landlocked country located in Central Europe.