Which of the following components is a primary cause of eutrophication?a.Oil spills.b.Nutrient runoff from agriculturec.Thermal pollutiond.Industrial pollution

The primary cause of eutrophication among the options provided is b. Nutrient runoff from agriculture.

Here's a step-by-step explanation:

1. Eutrophication is a process driven by the enrichment of water by nutrients, especially compounds of nitrogen and/or phosphorus.

2. These nutrients can come from many sources, but one of the most significant sources in many parts of the world is agricultural runoff. This runoff can contain fertilizers used in agriculture, which are rich in nitrogen and phosphorus.

3. When these nutrients reach bodies of water, they can stimulate an overgrowth of algae, a process known as an algal bloom.

4. The algal bloom can block sunlight from reaching other plants in the water, causing them to die and decompose.

5. The decomposition process consumes oxygen in the water, leading to low levels of oxygen. This condition, known as hypoxia, can kill fish and other aquatic life.

6. Therefore, nutrient runoff from agriculture is a primary cause of eutrophication.

Oil spills, thermal pollution, and industrial pollution can also harm aquatic ecosystems, but they are not the primary causes of eutrophication.