National Parks Are Increasingly Becoming Like Islands

National Parks are increasingly becoming like islands.What is meant by this is:

A) During peak seasonal use,National Parks are like islands of human activity that resemble urban areas,in a otherwise rural landscape.
B) Most National Parks are located on islands.
C) National Parks are like sanctuaries that successfully maintain healthy populations of species such as grizzly bears and wolves.
D) National parks are increasingly becoming islands of natural habitat surrounded by human development that limits the areas in which wild animals may range,forcing them into isolated populations.