This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal tract, 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: Aerophagia (var. aerophagy) is a condition of excessive air swallowing, which goes to the stomach. Aerophagia may also refer to an unusual condition where the primary symptom is excessive flatus, belching is not present, and the actual mechanism by which air enters the gut is obscure.Aerophagia in psychiatry is sometimes attributed to nervousness or anxiety. Reference: GHAI Essential pediatrics, 8th edition', 'role': 'assistant'}]