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: Surgery
[{'content': 'At what age baby with congenital hypertrophic pyloric stenosis show symptoms \nSelect and explain. \nA. At the time of birth, B. First week, C. 3rd to 4th week, D. Second month', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Baby show the symptoms of projectile vomiting, olive shaped mass and visible peristalsis', 'role': 'assistant'}]