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: Pathology
[{'content': 'Which is the most important feature to differentiate carcinoma in situ from invasive carcinoma? \nSelect and explain. \nA. Metastasis, B. Anaplasia, C. Number of mitotic spindles, D. Breach in basement membrane', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Penetration of basement membrane is the hallmark of invasive carcinoma. In carcinoma in situ basement membrane is not\xa0\xa0involved.', 'role': 'assistant'}]