This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gastrointestinal System Including Diarrhea, Subject name: Pediatrics
[{'content': 'A two-year-old child presents with persistent diarrhea, acidic stools and presence of one percent of reducing substance in the fresh stools. What is the most probable diagnosis? \nSelect and explain. \nA. Cystic fibrosis, B. Lactose intolerance, C. Rotavirus induced diarrhea, D. Intestinal tuberculosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Presence of acidic stools with reducing substance positive, suggests a diagnosis of lactose intolerance.', 'role': 'assistant'}]