This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2019, Subject name: Social & Preventive Medicine
What is Saturation index? 
Select and explain. 
A. Used to assess the Air quality by measuring concentration of pollutants., B. Used to assess the water quality by estimating hardness, total dissolved solids, alkalinity and pH., C. Used to assess the Soil quality that whether it is good for growing crops., D. Used to assess the Milk quality by estimating the bacterial count in it.
B: Used to assess the water quality by estimating hardness, total dissolved solids, alkalinity and pH.
Answer: B: Used to assess the water quality by estimating hardness, total dissolved solids, alkalinity and pH. 
Explanation: Langlier saturation index indicates degree of saturation of CaCO3 in water Used in industry to stabilize water. LSI is based on 1) pH of water 2) Total dissolved solids 3) Alkalinity 4) Calcium concentration 5) water temperature - LI positive - it leads to deposition & scaling - LI negative - it leads to corrosion - LI should be kept zero - to avoid corrosion & scaling