This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Pediatrics
Persistent diarrhoea is defined as diarrhoea lasting more than? 
Select and explain. 
A. 7 days, B. 14 days, C. 21 days, D. 28 days
B: 14 days
Answer: B: 14 days 
Explanation: Ans. (b) 14 days