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': 'Hallmark of breast malignancy on mammography : \nSelect and explain. \nA. Low density lesion, B. Smooth margin, C. Clusters of micro calcification, D. Popcorn calcification', 'role': 'user'}, {'content': "Answer: C \nExplanation: Microcalcification's is pathognomonic sign for breast carcinoma. It may be seen in 30% cases of invasive carcinoma and 95% of cases of DCIS (granular and casting).", 'role': 'assistant'}]