This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Hardness of water is contributed by following salts except – 
Select and explain. 
A. Calcium gluconate, B. Magnesium chloride, C. Calcium sulfate, D. Magnisum bicarbonate
A: Calcium gluconate
Answer: A: Calcium gluconate 
Explanation: None