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': 'An undifferentiated malignant tumour on immunohistochemical stain shows cytoplasmic positivity of most of the tumor cells for cytokeratin. The most probable tumor is: \nSelect and explain. \nA. Sarcoma, B. Lymphoma, C. Carcinoma, D. Malignant Melanoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: . Carcinoma', 'role': 'assistant'}]