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': 'LEAST diagnostic test for breast tumours: March 2013 \nSelect and explain. \nA. Chest X-ray, B. Biopsy, C. USG, D. Mammography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A i.e. Chest X-ray', 'role': 'assistant'}]