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: ENT
Which sign is seen due to thrombosis of mastoid emissary veins? 
Select and explain. 
A. Battle sign, B. Gresinger sign, C. Irwin Moore Sign, D. Hennebe's sign
B: Gresinger sign
Answer: B: Gresinger sign 
Explanation: Ans. is'b'i.e., Gresinger sign (Ref Dhingra 5th/e p. 95) Griesinger's sign: - Edema over the posterior pa of mastoid due to thrombosis of mastoid emissary veins.