This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'A 67 year nude smoker presents with haemoptysis and cough. Bronchoscopic biopsy revealed un-differentiated tumour. The immunohistochemical marker that can be most helpful is- \nSelect and explain. \nA. Calretinin, B. Vimentin, C. Cytokeratin, D. GGt', 'role': 'user'}, {'content': 'Answer: C \nExplanation: TEXT BOOK OF PATHOLOGY HARSHMOHAN 6TH EDITION PG NO 16 Epithelial tumors are stained by pankeratin or cytokeratin (high or low MW) <\\p>', 'role': 'assistant'}]