Eutrophication is caused by
a.
an increase in nutrients
b.
a decrease in nutrients
c.
the introduction of new species of animals
d.
the introduction of new species of plants

The right option is; a. an increase in nutrients

Eutrophication is caused by an increase in nutrients

Eutrophication refers to when a body of water (such as a river)  becomes rich in nutrients and minerals and therefore has excessive growth of algae and aquatic plants and thus, a diminished oxygen content to the detriment of other organisms living in the water body. Eutrophication is usually caused by the release of sewage or detergents, and fertilizers that contains phosphate or nitrate into an aquatic ecosystem.