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
Battle's sign is: 
Select and explain. 
A. Sub-conjunctival ecchymosis, B. Sub-lingual ecchymosis., C. Palatal ecchymosis, D. Ecchymosis in the mastoid region
D: Ecchymosis in the mastoid region
Answer: D: Ecchymosis in the mastoid region 
Explanation: None