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: Pediatrics
Useful in acute diarrhoea: 
Select and explain. 
A. Zinc, B. Magnesium, C. Calcium, D. Potassium
A: Zinc
Answer: A: Zinc 
Explanation: The World Health Organization (WHO) and UNICEF recommend daily 20 mg zinc supplements for 10-14 days for children with acute diarrhea, and 10 mg per day for infants under six months old, to curtail the severity of the episode and prevent further occurrences in the ensuing two to three months, thereby decreasing the morbidity considerably.
One out of every five children who die of diarrhea worldwide is an Indian. Daily around 1,000 children die of diarrhea in India, which means 41 children lose their lives every hour.