Algal blooms occur due to the presence of an excess amount of nutrients, like phosphorus, in fresh water. how does excess phosphorus get into fresh water?

a)
the nutrients are added to the water by fishermen to feed the fish.
eliminate

b)
the nutrients leak into fresh water from oil refineries in the vicinity.

c)
the nutrients are a part of the fertilizers that are often washed away into ponds.

d)
the nutrients are formed by the decomposition of organic wastes dumped into fresh water.