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': "Battle's sign is: \nSelect and explain. \nA. Sub-conjunctival ecchymosis, B. Sub-lingual ecchymosis., C. Palatal ecchymosis, D. Ecchymosis in the mastoid region", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]