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': "Stellwag'sign is: \nSelect and explain. \nA. Absence of normal winking., B. Failure of convergence of eye balls., C. Exophthalmos., D. None.", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]