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': 'Most common site for metastasis in choriocarcinoma \nSelect and explain. \nA. Lungs, B. Brain, C. Liver, D. Spine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]