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': 'Ca 125 is used in diagnosis of - \nSelect and explain. \nA. Ovarian cancer, B. Gall bladder cancer, C. Carcinoids, D. Bronchogenic cancer', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]