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
[{'content': 'Most common cause of severe hematemesis in a child is – \nSelect and explain. \nA. Portal hypertension, B. Peptic ulcer, C. Mallory weiss syndrome, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: "Massive\xa0 hematemesis in a child is almost always due to variceal bleeding". Variceal bleeding is due to portal hypertension.', 'role': 'assistant'}]