Which of the following counties is NOT in the list of Tropical counties?

Nassau County is not considered a tropical county within the context of Florida's distinct climatic regions. The designation of tropical counties typically applies to areas that experience a more consistently warm climate with specific environmental conditions favorable for tropical ecosystems.

South Dade, Miami-Dade, and the Florida Keys are all parts of the southern region of Florida, which is characterized by a tropical climate. These areas exhibit significant warmth, high humidity, and a unique arrangement of flora and fauna that fits the definition of tropical. In contrast, Nassau County, located in the northern part of Florida, does not have the same tropical climate attributes, making it distinct from the other listed counties. Understanding the geographical and climatic differences helps clarify why Nassau County does not fall into the same category as the others mentioned.