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': 'Radon exposure is known to cause \nSelect and explain. \nA. Carcinoma lung, B. Leukemia, C. Carcinoma colon, D. Brain tumors', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ETIOLOGY OF CANCERS OF LUNG\n■ Chromium,\n■ Nickel, other metals\n■ Tobacco smoking,\n■ Ionising radiation (uranium)\n■ Radon.\n■ Asbestosis (May predispose to Bronchogenic carcinoma, mesothelioma, gastrointestinal cancer). Suspected Carcinogens', 'role': 'assistant'}]