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: Radiology
[{'content': 'Investigation to diagnose stage-I carcinoma breast: \nSelect and explain. \nA. B/ L mammogram, B. X-ray chest, C. Bone scan, D. Liver scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. B/L mammogram', 'role': 'assistant'}]