Eutrophication is nutrient enrichment of a freshwater body, usually from phosphorus and nitrogen inputs like fertilizer runoff, sewage, and detergents, which fuels excessive plant and algal growth. This rapid blooming of algae and other aquatic plants changes the ecosystem in several connected ways. The dense algal blooms reduce light penetration and, when they die and decompose, bacteria break down the organic matter and consume a lot of the dissolved oxygen in the water. That oxygen depletion creates hypoxic conditions, often forming dead zones where many aquatic species cannot survive, leading to fish kills. The shading and altered habitat from the dense vegetation also disrupt native communities and overall biodiversity. Since each of these outcomes is a typical result of nutrient-driven eutrophication, the best overall description is that all of the above occur.

Conservation status categories describe how at risk a species is of disappearing. Threatened is the umbrella label for species at risk of extinction in the near future, meaning they are in danger now or could become extinct if pressures continue. It appropriately spans both current danger and the forecast of possible extinction. Extinction is the outcome—the species no longer exists anywhere. Endangered is a more specific, high-risk subset within threatened, indicating immediate danger of extinction, but the question's wording fits the broader 'threatened' category. Hazardous waste has nothing to do with a species’ conservation status.

Conserve means to keep and protect something from damage, change, or waste. It involves using resources carefully and preserving their value so they don’t run out or deteriorate. For example, conserving water means fixing leaks and not letting taps run unnecessarily, while conserving energy means turning off lights when not needed or using efficient appliances. The other options don’t fit: deplete means to use up resources, reducing what’s available; an eyesore is something unsightly; global warming refers to the long-term increase in Earth’s average temperature due to greenhouse gases.

Resources that exist in the natural environment and can be used by people are called natural resources. Minerals and forests are classic examples because they are materials found in a location that people can extract or harvest for use, whether for metals, energy, construction, or other needs. Some natural resources, like minerals, are non-renewable, while others, like forests, can be renewed if managed sustainably. This helps distinguish natural resources from related terms: renewable energy refers to energy sources that replenish, rather than to the broad category of resources themselves; ecosystem services are the benefits people obtain from ecosystems (such as clean water or flood protection), not the resources directly; and biodiversity is the variety of living organisms in an area, which underpins resources but is not the resources themselves.