In wildlife conservation, which one among the following best defines an 'endemic' species?

Options

A. A.When the critical number of a species declines in a forest due to parasitic attack
B. B.A species which is cosmopolitan and can be commonly found in a biosphere
C. C.An endangered species which is found in a few restricted areas on the Earth
D. D.A species confined to a particular region and not found anywhere else