This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mechanical injuries, Subject name: Forensic Medicine
Battle sign - 
Select and explain. 
A. Periorbital ecchymosis, B. Mastoid bleed, C. Nose bleed, D. Bleed from tympanic membrane
B: Mastoid bleed
Answer: B: Mastoid bleed 
Explanation: The synopsis of forensic medicine & toxicology;Dr k .s narayan reddy; 28th edition; pg.no. 107; A bruise behind the ear may indicate a basal fracture rather than a direct blow behind the ear .(BATTLE 'S SIGN) It is an example of ectopic bruising or percolated contusion.