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: Surgery
[{'content': 'Specific marker for prostatic cancer is \nSelect and explain. \nA. Prostate specific antigen, B. LDH, C. Chromogranin, D. CA 19-9', 'role': 'user'}, {'content': 'Answer: A \nExplanation: PSA + DRE is the best method to screen prostate cancer.', 'role': 'assistant'}]