This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallbladder, Subject name: Surgery
Mercedes Benz sign or Seagull sign is seen in: 
Select and explain. 
A. Gallstones, B. Renal stones, C. CBD stones, D. Hydatid cyst
A: Gallstones
Answer: A: Gallstones 
Explanation: Mercedes Benz sign or Seagull sign The centre of Gallstone may contain radiolucent gas in a triradiate or biradiate fissure, this gives rise to characteristic darkshapes on radiograph- the Mercedes Benz sign or Seagull sign.