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': 'Which of the following sign is not seen in hypertrophic pyloric stenosis \nSelect and explain. \nA. String sign, B. Shoulder sign, C. Double track sign, D. Troseier sign', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]