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': 'Which of the following features on mammogram would suggest malignancy – \nSelect and explain. \nA. Well defined lesion, B. A mass of decreased density, C. Areas of speculated microcalcifications, D. Smooth borders', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]