Explanation:

To reduce the problem of eutrophication, the following steps can be effective:

Creating wetlands around a water body: This can help reduce eutrophication as wetlands act as natural filters, absorbing excess nutrients that would otherwise contribute to eutrophication in the water body.

Reducing air pollution: This step is indirectly related to eutrophication. Air pollution can contribute to the deposition of nitrogen compounds in water bodies, exacerbating eutrophication. Therefore, reducing air pollution can have a positive impact.

Using lakes for aquaculture: This might actually contribute to eutrophication, rather than reduce it. Aquaculture often involves the addition of nutrients and organic matter to the water, which can increase the risk of eutrophication.

Therefore, steps 1 and 2 can be taken to reduce eutrophication, but step 3 may not be effective in this regard.