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': 'The commonest malignant tumour of the lids is: \nSelect and explain. \nA. Basal-cell carcinoma, B. Squamous cell carcinoma, C. Adenocarcinoma, D. Melanocarcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Basal-cell carcinoma', 'role': 'assistant'}]