Adaptive radiation occurs in

In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges and opens environmental niches. Adaptive radiation occurs in sexually reproducing population to create multitude new forms and not in predator free area, small and isolated populations and flightless and asexually reproducing populations. Thus, option D is correct and other options are wrong.