Alichen is best described as:
a) a plant.
b) a fungus.
c) an alga.
d) a symbiotic relationship between algae or cyanophyta; and fungi.

what are the choices?

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.