The correct answer is D. all of the above.
Water pollution is caused by the introduction of harmful substances or excessive amounts of substances into water bodies, such as rivers, lakes, oceans, aquifers and groundwater. These substances can be either naturally occurring or man-made, and can have a negative impact on human health and the environment.
Agricultural discharges are a major source of water pollution. They can include fertilizers, pesticides, herbicides, and animal waste. These substances can runoff into waterways and contaminate drinking water supplies, harm aquatic life, and cause algae blooms.
Sewage and other wastes are also a major source of water pollution. Sewage is wastewater from homes and businesses that contains human waste, as well as detergents, cleaning products, and other chemicals. When sewage is not properly treated, it can contaminate drinking water supplies, harm aquatic life, and cause disease.
Industrial effluents are wastewater from factories and other industrial facilities. They can contain a variety of harmful chemicals, including heavy metals, solvents, and acids. Industrial effluents can contaminate drinking water supplies, harm aquatic life, and cause disease.
In addition to these three major sources, water pollution can also be caused by oil spills, mining activities, and urban runoff.