This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Trauma, Subject name: Surgery
[{'content': "A patient admitted in casualty after RTA- shows bruising behind the mastoid- This sign is known as. \nSelect and explain. \nA. Prehn sign, B. Battle sign, C. Catel Sign, D. Dietel's sign", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Battle sign* Battle sign is due to Fracture of base of skull* Middle cranial fossa fracture is associated with Battle sign', 'role': 'assistant'}]