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': "True about Hirshprug's disease - \nSelect and explain. \nA. Aganglionic segment is contracted not dilated, B. Descending colon is most common site, C. Barium enema is diagnostic, D. Barium enema shows calcification", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Aganglionic segment is contracted not dilated", 'role': 'assistant'}]