Answer:
B.
Step-by-step explanation:
Florida's climate itself hasn't particularly changed a bunch, but in the 20th century the population of Florida has increased. Plus D and C are easy to rule out. The easiest explanation for the panther's decline is the fragmentation of their habitat, and human interaction with the environment, not hunting per se. Good news is that the Florida panther's population has gone up to over 100!
Best of luck, and feel free to ask for any clarification.