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: Medicine
[{'content': 'Tumor marker relevant with ovarian carcinoma is: \nSelect and explain. \nA. CA-125, B. CA-19.9, C. CD-30, D. CD-25', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (CA 125) : Manual of Clinical Surgery by Kirk CA 125 is the most commonly used tumor marker for ovarian cancer - Kirk CA-125 is found in derivatives of Coelomic epithelium, including pleura pericardium and peritoneum but is not detected in normal ovarian tissue.', 'role': 'assistant'}]