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': 'On mammogram all of the following are the features of a malignant tumor except – \nSelect and explain. \nA. Spiculation, B. Microcalcification, C. Macrocalcification, D. Irregular mass', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]