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: Ophthalmology
[{'content': 'One of the early symptoms of orbital involvement by basal cell carcinoma of the lid is: \nSelect and explain. \nA. Diplopia, B. Defective vision, C. Proptosis, D. Severe pain', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Diplopia', 'role': 'assistant'}]