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
Which among the following is marker of carcinoma? 
Select and explain. 
A. Cytokeratin, B. Vimentin, C. Calretinin, D. CD 45
A: Cytokeratin
Answer: A: Cytokeratin 
Explanation: Cytokeratin is present in abundance in epithelial cells. Hence it serves as a useful marker of carcinoma.