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 said to be beneficial for which disease: 
Select and explain. 
A. Cardiovascular disease, B. Renal disease, C. Diabetes, D. All of the above
A: Cardiovascular disease
Answer: A: Cardiovascular disease 
Explanation: Studies have shown an inverse relationship between the hardness of drinking water and the death rate from cardiovascular diseases. Diseases believed to be affected include atherosclerotic hea disease, hypeension, sudden deaths of cardiovascular origins etc. Ref: Park 21st edition, page: 672.