Natural water that exposed to limestone is

Answer: Option A

Natural water that is exposed to limestone is Calcareous water.
When water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicarbonates, and sulphates, then that water is termed calcareous water.
It is not a health risk but is a nuisance because of mineral buildup on plumbing fixtures' and poor soap and or detergent performance.