The correct answer is a nutrient runoff.
Nutrient runoff is a major reason for eutrophication of surface waters, in which extra amount of nutrients, generally phosphorus or nitrogen, instigate growth of algae. Sources of nutrient pollution involve surface runoff from pastures and farm fields, emissions from combustion, and discharges from septic tanks.
SE LE CONOCE COMO IRRITABILIDAD
Los seres vivos tienen la capacidad de responder a una variedad de estímulos tanto del medio exterior como del medio interno. Esta capacidad de respuesta se denomina irritabilidad, porque es diferente a otro tipo de respuestas que se observan en la naturaleza.
That should make it more clear . Its the same thing . Both seta and cheta or chaete means bristles. I think the term can be used interchangeably.