B or d.... hope this helps:)
Not sure if I'm correct but my best guess is the cell membrane seeing as it surrounds the cell itself and is responsible for allowing certain molecules to diffuse in or out of the cell. Good Luck! :)
Answer:
I think the correct answer is D
It is an essential element for plant life, but when there is too much of it in water, it can speed up eutrophication (a reduction in dissolved oxygen in water bodies caused by an increase of mineral and organic nutrients) of rivers and lakes. Soil erosion is a major contributor of phosphorus to streams.
