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: Social & Preventive Medicine
[{'content': 'Overall most common cancer in wold \nSelect and explain. \nA. Lung cancer, B. Colon cancer, C. Breast cancer, D. Thyroid carcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]