Eutrophication is often the result of
a. increases in animal populations
b. lack of oxygen in the water
c. fertilizer runoff entering aquatic ecosystems
d. a decrease in phytoplankton populations

c. fertilizer runoff entering aquatic ecosystems

Eutrophication is a phenomena which occurs when the water body becomes over-enriched with the minerals and nutrients which get deposited due to surface run off. This results in the excessive growth of algae and other plants, the available oxygen present in the water depletes which results in the mortality of the aquatic animals.

The fertilizers which are used for the purpose of agriculture, are taken away by the water and wind erosion. This water gets added up to the water body. Hence, resulting in eutrophication.  

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.

rising temperatures because when water vapor in the air is cooled, it condenses. it turns back into a liquid and attaches to dust particles in the air. these very small water droplets group together to form clouds