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': 'The commonest cause of vomiting in a one month old infant is - \nSelect and explain. \nA. Pyloric stenosis, B. Cardiac chalasia, C. Aerophagy, D. Gastro-esophageal reflux', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Aerophagy", 'role': 'assistant'}]