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
Most common type of cancer gall bladder in a patient with gallstone- 
Select and explain. 
A. Adenocarcinoma, B. Squamous carcinoma, C. Sarcoma, D. None
A: Adenocarcinoma
Answer: A: Adenocarcinoma 
Explanation: None