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': 'The element used as target material in mammography is which of the following? \nSelect and explain. \nA. Copper, B. Tungsten, C. Molybdenum, D. Aluminum', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Two target materials used for mammography are molybdenum (Z 42) and rhodium (Z 45), the former being the most common. Molybdenum has a K-edge at 20 keV and produces characteristic radiations at 17.4 and 19.6 keV. In order to achieve a more nearly monoenergetic beam, the emerging spectrum is filtered by the same material (Molybdenum, about 0.03 mm thick).', 'role': 'assistant'}]