This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding from the GUT and diseases of esophagus, Subject name: Medicine
[{'content': "Most common cause of hematochezia in children? \nSelect and explain. \nA. Rectal polyp, B. Meckel's diveiculum, C. Necrotizing enterocolitis, D. Acute gastritis", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Causes of Lower GI bleeding in children - Neonate = anal fissure 1 month - 1 year = anal fissure 1 year - 2 years = Rectal polyp 2 years = Rectal polyp', 'role': 'assistant'}]