A is correct because California is a biodiversity hot spot due to its unique geography, climate, geologic history and size.
B is correct, as Hawaii’s isolation and geological activity shape the biodiversity of the islands. It has over 25,000 unique species.
C is also correct, as the Florida Everglades are known for their large biodiversity and shrinking habitats due to damming and climate change
Therefore, the answer is D: all of the above.