Why Do Kidney Stones Form

Why do kidney stones form?

A) Calcium salt levels in the kidneys reach saturated levels and precipitate.
B) Magnesium levels in the kidneys reach saturated levels and precipitate.
C) Organic toxins build up in the kidney and precipitate.
D) Chloride ions reach saturated levels in the kidney and precipitate.
E) All of the above ions and molecules contribute to the formation of kidney stones.