The correct answer is a) Eutrophication.
Eutrophication is the excessive growth of algae in water bodies due to pollution. It is caused by the addition of nutrients, such as nitrates and phosphates, to the water. These nutrients come from fertilizers, sewage, and other sources. When there are too many nutrients in the water, algae grow rapidly. This can lead to a number of problems, including the death of fish and other aquatic life, the contamination of drinking water, and the loss of recreational opportunities.
Aquaculture is the farming of aquatic organisms, such as fish, shellfish, and algae. It is a major source of food for humans and other animals. Aquaculture can be done in a variety of ways, including in ponds, tanks, and cages.
Hydroponics is a method of growing plants without soil. Plants are grown in a nutrient-rich solution, which can be either in a liquid or a solid form. Hydroponics is often used to grow crops in areas where there is little or no soil, such as in deserts or on rooftops.
Upwelling is the upward movement of water in the ocean. It is caused by the wind blowing across the surface of the water. Upwelling brings nutrients from the deep ocean to the surface, which can support a variety of marine life.