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': 'A 56-year-old chronic smoker, mass in bronchus resected. What is the possible marker- \nSelect and explain. \nA. Cytokeratin, B. Vimentin, C. Epithelial membrane Cadherin, D. Leukocyte', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Squamous cell carcinoma is most commonly found in men and is closely correlated with a smoking histoty.\nHistologically, it is characterized by keratinization and intracellular bridges.\nCytokeratin is a marker for keratinizing cells.', 'role': 'assistant'}]