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: Gynaecology & Obstetrics
[{'content': 'Tumor marker most helpful in follow up of a case of Epithelial carcinoma of ovary is : \nSelect and explain. \nA. CA - 125, B. Serum Alpha Fetoprotein, C. Serum human chorionic gonadotropin, D. Human Placental Lactogen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: CA - 125', 'role': 'assistant'}]