This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal obstruction, Subject name: Surgery
[{'content': 'Commonest cause of colonic obstruction in neonates is: \nSelect and explain. \nA. Meconium ileus, B. Aganglionic colon, C. Ileal atresia, D. Volvulus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Aganglionic colon is Commonest cause of colonic obstruction in neonates.', 'role': 'assistant'}]