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: Gynaecology & Obstetrics
[{'content': "The most common site of vulval cancer: \nSelect and explain. \nA. Labia majora, B. Labia minora, C. Prepuce of the clitoris, D. Bartholin's gland", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]