You Are "Living Off the Grid" Meaning That You Are

You are "living off the grid" meaning that you are not using any public utilities: no water supply, sewer connection, natural gas, or electricity.You do have a septic tank, whose pipe carries sewage underground where it is released over a wide area, the leaching field.There is also a small pond out there that you have stocked with fish.However, you notice that the fish are floating dead in the water, and the pond has a green scum on it.What happened?

A) There is oxygen depletion in the pond due to the leakage of phosphates and other compounds from your septic tank.
B) There are not enough nutrients in the water, so the fish died.
C) Chemical toxins from your septic tank cleaner have killed the fish.
D) The fish died due to a lack of calcium, which then caused the algae to overgrow.