Which best describes adaptive radiation

The answer is; Biodiversity resulting from few ancestors

Adaptive radiation occurs when a population is subjected to a large natural environment with spatial ecological variations. The parts of the population in the different ecologies begin to adapt to their local environments. Due to non-random mating across the large populations, this causes the different populations from the large population to speciate within their local environments. They, therefore, diverge to different species sharing a common ancestor.  

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.