This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'For determination of sex, smear is taken from \nSelect and explain. \nA. Buccal mucosa, B. Vagina, C. Skin, D. Nose', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Buccal mucosa', 'role': 'assistant'}]