Which of the following are non-point sources of nutrients to surface waters?

Non-point sources of nutrients to surface waters are those where the pollutants originate from diffuse sources rather than a single point of discharge. In this context, farms are a notable example of non-point sources, as they can contribute nutrients like fertilizers and animal waste across broad areas through runoff rather than from a single identifiable location.

Storm sewers in small towns typically represent a more concentrated point of discharge and are thus classified as point sources, while wastewater treatment plants discharge water from a specific point after treatment. As a result, both storm sewers and wastewater treatment plants represent point source pollution.

By identifying farms as a non-point source, it becomes clear why the answer encompasses them, reinforcing the classification of pollution sources based on how widely the contaminants are dispersed in the environment. Therefore, the correct answer acknowledges the nature of farms as non-point sources of nutrient pollution to surface waters while excluding the point sources represented by storm sewers and wastewater treatment plants.