This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
Hardness of drinking water should be? 
Select and explain. 
A. >3, B. <1, C. 3-Jan, D. >6
C: 3-Jan
Answer: C: 3-Jan 
Explanation: Drinking water should be moderately hard.Softening of water is recommended if hardness ecxeeds 3mEq/l. Soft water- <1 mEq/l Moderately hard- 1-3 mEq/l Hard water- 3-6mEq/l Very hard water- >6mEq/l Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 727