2. What is it called when certain species have evolved such intimate symbiotic relationships that individuals of elther species cannot survive without one another? facultative
mutualistic
parasitic
obligate​

The water pollution that is most likely to occur is Nutrient pollution

Pollution can be defined as the addition of materials or energy (pollutants) to the environment that damages it, making it undesirable or unfit for life. There are different types of pollution which includes:

--> Air pollution

--> Radiation pollution

--> soil pollution and

--> water pollution.

WATER POLLUTION is defined as the type of pollution that occurs when pollutants are being released into water bodies such as streams, lakes, ocean, beaches making it unsafe to use for both human and aquatic life activities. Depending on the type of pollutants, there are also different types of water pollution, these include:

NUTRIENT pollution occurs when there is EXCESS of it in the water bodies through organic fertilizer or compost manure from the leaves of the cut down trees and shrubs. When nitrates from the agricultural waste gets into the water body(lake)  it can cause a drastic increase in aquatic plant growth, especially algal growth. This excessive growth can lead to a decrease in oxygen level of water they by affecting the aquatic life of the lake.

Therefore the CORRECT OPTION is A Nutrient pollution.

Option B is wrong because sediment pollution is a type that involves loose sand, clay, silt, and other soil particles that are carried from a site by runoff water not from cut down trees.

Option C is wrong because toxic or chemical pollution is caused by chemicals from industrial wastes.

Option D is wrong because it is caused by natural existing bacteria in the water bodies and are capable of causing disease when ingested. Example Vibro cholera bacteria.

Learn more about water pollution here