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
When the level of hardness in water is around 150-300 mg / litre it is classified as 
Select and explain. 
A. Very hard water, B. Soft water, C. Moderately hard water, D. Hard water
D: Hard water
Answer: D: Hard water 
Explanation: None